Lister Engine Forum

Lister Engines => Listeroid Engines => Topic started by: BruceM on December 31, 2014, 08:31:13 PM

Title: DES 8/1 Propane Conversion project
Post by: BruceM on December 31, 2014, 08:31:13 PM
I'm going to attempt a propane conversion of a DES 8/1.  Using an Impco propane carburetor, lowered compression, spark in the injector hole.  I'm planning on about 750 rpm operation.  Application is AC power and compressed air for an off grid homestead in very rural 5600 ft elevation AZ.  ST-3 planned, 2200 watts continuous is sufficient.

Today I'm trying to find a 16-17" cast iron sheave for a B-belt in order to drive an LaPlant LP205 two stage compressor at about 800 rpm or a bit less.

Anybody know of a good source for large sheaves besides Grainger?  They have a browning but it's $200.

Has anyone tried driving a B Belt direct on the flywheel? I'm thinking there might be sufficient surface area to do that for a modest load.  I'm considering this for the ST-3 drive.  Lots more flexibility in sheave size.  A 10" sheave would match my desired 750 rpm.  A single B belt is more than adequate according to my belt chart.
Title: Re: DES 8/1 Propane Conversion project
Post by: mike90045 on December 31, 2014, 09:50:21 PM
I would check the de-rate data for Propane and 5600 ft elev.   You may not make 2200watts at 750 rpm
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on December 31, 2014, 10:26:13 PM
You may be right, Mike, it depends on how low I have to drop the compression.  One article I found suggests about 3.5% loss in power per point of compression. So if I have to lower to a compression ratio of 10 from 17, that would be a 24.5% power loss.  If a compression ratio of 12:1 is OK, then a 17.5% loss. The increase in rpm is good for about 15% increase.  So a net 2.5-10% loss over my 6/1 on diesel at the same elevation. I have plenty of headroom on my 6/1 so I think that will be OK. 









Title: Re: DES 8/1 Propane Conversion project
Post by: Tom on December 31, 2014, 11:37:42 PM
Up at that elevation you might be able to run 14:1 with no issues and preserve some of that precious HP.
Title: Re: DES 8/1 Propane Conversion project
Post by: cujet on January 01, 2015, 12:24:05 AM
Just out of curiosity, why not use the diesel injector set at the idle or pilot setting as the propane ignition? That way, you can retain good compression, but probably not full compression. Possibly 15 to 1 at your altitude. Your loads are modest, so you might be able to pull it off. Just thinking aloud here, but an intake restriction would help prevent propane detonation at higher compression ratio's.
Title: Re: DES 8/1 Propane Conversion project
Post by: buickanddeere on January 01, 2015, 02:33:47 AM
Just out of curiosity, why not use the diesel injector set at the idle or pilot setting as the propane ignition? That way, you can retain good compression, but probably not full compression. Possibly 15 to 1 at your altitude. Your loads are modest, so you might be able to pull it off. Just thinking aloud here, but an intake restriction would help prevent propane detonation at higher compression ratio's.

Best Idea here yet.
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on January 01, 2015, 05:20:53 PM
Thanks for the good suggestion, cujet. That's a good way to get around the propane/diesel preignition issue. I might consider that for my own engine, but I'm going to try 100% propane on the DES 8/1.

Thanks for the higher compression suggestion, buickanddeere. 


Title: Re: DES 8/1 Propane Conversion project
Post by: carlb23 on January 01, 2015, 09:33:40 PM
While I don't get to use my generator much since our power company doesn't have too many power outages, I setup my 6/1 with diesel pilot ignition and natural gas fumigation.  I run enough natural gas (set via a needle valve) to produce approximately 1800 watts with the rack in the mostly closed position, just enough diesel to keep the engine running.  My normal loads are 1800 to 1900.  If the load increases the amount of natural gas does not change the rack just opens to add some more diesel to make up the difference. 

this system is both simple and reliable.  I use an electronic gas valve (off an old gas furnace) that is powered by the generator so if the engine fails or a belt brakes or any other malfunction that would cause the generator to stop producing power it will automatically close the gas valve stopping the flow of natural gas. 
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on January 02, 2015, 03:45:56 AM
I think your setup is sweet, Carl.  Natural gas and diesel are a sweet mix, up to 85% NG is possible as I recall. 

Both my future neighbor, and I have severe MCS, thus we're living in the sticks surrounded by high desert grazing land.  Handling diesel fuel is still hard for me as well, I miss the biodiesel I ran the first few years on my Listeroid.  No sources for that now within 100 miles.  Propane is an ideal fuel for our situation; it burns clean, no fuel handling/transport issues.

Cujet's idea is intriguing, I wonder what the max propane level would be to still allow enough compression for the diesel fuel to ignite.

I'm going to try a cheap ($50) made in China, shielded CDI spark ignition system (designed for RC airplanes) and see if I can get along with it. It doesn't take much time near a typical ignition system to set off my epilepsy.  Plan B is a homemade version of Mark Cherry's smartplugs (smartplugs.com).  It's sort of a modern, compact, platinum catalytic version of hot tube ignition.  I used a copy of Mark's basic patent method successfully on a small Honda outboard conversion about 10 years ago.

Best Wishes,
Bruce

Title: Re: DES 8/1 Propane Conversion project
Post by: Tom on January 02, 2015, 05:19:59 AM
Another possible ignition would be a CDI from a pit bike engine. Every thing needed could be had for < $30.
Title: Re: DES 8/1 Propane Conversion project
Post by: dieselgman on January 02, 2015, 07:37:18 AM
Just for another variation in thinking... The HR gas engines drop the compression ratios with a dramatically concave piston crown. I would bet that this piston mod could quite easily be done with a CS diesel piston. Direct injection head design is also a preferable configuration for running spark ignition gas fuels.

Ignition timing becomes critical, and combustion stresses greatly increased in a gas fueled setup. We use special nodular iron rings, hardened valve seats, and specially hardened valves in our natural gas engines to give them a reasonable life expectancy. Timing has to be adjusted for propane vs natural gas, they have pre-ignition issues otherwise. We also use inlet air restrictors to help control that destructive pre-ignition (detonation) tendency.

Dieselgman
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on January 02, 2015, 03:12:52 PM
Thanks for the ideas, guys.
I've read about intake air restrictions being used in propane conversions on the IMPCO website-  could someone please explain why that is used?
Is this because ignition timing needs to be changed with throttle position but can't be in a typical retrofit?  I can manage that electronically if I must.
Title: Re: DES 8/1 Propane Conversion project
Post by: veggie on January 03, 2015, 02:33:59 AM

Has anyone tried driving a B Belt direct on the flywheel? I'm thinking there might be sufficient surface area to do that for a modest load.  I'm considering this for the ST-3 drive.  Lots more flexibility in sheave size.  A 10" sheave would match my desired 750 rpm.  A single B belt is more than adequate according to my belt chart.


BruceM

I have done this on many of my systems.
Here is a unit I built for sale 2 years ago. It uses two "B" series belts to drive a 4kw generator.
The belts did not flop on their sides due to belt tension, however I would recommend using a "banded" belt where the
common backing keeps the belts from rolling.
https://www.youtube.com/watch?v=IbpiYeCJbNs (https://www.youtube.com/watch?v=IbpiYeCJbNs)

As you know V-belts are designed to carry load on the sides of the belt and not the inner surface. I counter this by over-sizing the belt drive by a factor of 2.
So, if 1 belt can normally carry the HP, I use 2 belts.
The surface area of the flywheel is so great that no slippage occurs.


My suggestion is to use a multi-ribbed "3V" series belt and a "3V" pulley on the ST-3 head. The 3V series belts have a much higher HP capacity than the "B" series. They also conform to smaller diameter pulley's (sheaves) better than a "B" series belt.

On my current listeroid I run a 2 groove (3V section) pulley on the generator and routinely pull 2.5 kw with no slippage (2.5 kw gen head).
When running the 4kw gen head on this engine I used a 3 banded "3V" belt and a 3 groove pulley.
If you want to over-engineer a bit, use a 3 groove pulley and a 3 banded 3V belt. Get the banded ones and not 3 individual belts.
the banded version is necessary to stop the belts from wandering and flopping over on their sides.

Here is another example of a unit I built using a 2 banded 3V belt.
The head has a 3 groove pulley but I only used 2 of them.
This generator can pull 3kw.
https://www.youtube.com/watch?v=f-hl2yfODME (https://www.youtube.com/watch?v=f-hl2yfODME)

cheers,
Veggie



Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on January 03, 2015, 03:51:56 AM
Thanks for sharing your experience with driving V-belts on the flat flywheel, Veggie!  Good to know it's been done successfully.  Since I'm driving a 10" pulley and only 2200 watts load for this setup, I may try a single B.

For a 17" single B pulley for the compressor drive,  jdv-belts.com  seems to be the best deal I can find.  I'll be using a LaPlante 2 stage compressor this time, as Eaton doesn't carry the nominal 5HP model I used on my system anymore.  Their current 5HP 2 stage unit is only rated 800-1000 rpm, a pretty narrow band and a bit too much power required.  HP ratings are for electric, and for gas, about double that is recommended. The LaPlante two stage LP205 is a good match for this setup, as rpm can be widely varied to match the engine, plus they have engineering data for power and air at all rpms.  see LPcompressor.com/pumps 





Title: Re: DES 8/1 Propane Conversion project
Post by: veggie on January 03, 2015, 04:15:45 AM

Nice units.
Will you be getting the "head Unloaders" which unload the compressor when the receiver tank is at full pressure ?

Veggie
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on January 03, 2015, 04:25:44 PM
Yes, the pneumatic head unloaders are essential to start the engine unloaded, and to "turn off" the compressor when it's belted but only the generator is needed.  On my setup I use an RC servo to control a toggle type air switch to turn on/off the unloaders/pilot valve.  Now that motorized ball valves are cheap I may go that way for control of the unloader "override".

On my automated setup I kept the ability for manual operation; the processor can be switched off and everything will operate just fine manually.  The engine can be started manually, and the processor switched on after.  After oiling or when removing/installing the compressor belt, I usually start it manually using the push button pneumatic controls just to eyeball things.
 
I leave the compressor unbelted unless I have a shop project to do as even unloaded it does affect fuel efficiency. The 500 gallon storage tank is plenty for everything but saw and sander use, or for my pneumatic string trimmer. 
Title: Re: DES 8/1 Propane Conversion project
Post by: carlb23 on January 03, 2015, 08:28:48 PM
you can also use this type of unloader if only running the compressor you can have the engine go to a low idle when not pumping.
Title: Re: DES 8/1 Propane Conversion project
Post by: dieselgman on January 03, 2015, 08:51:00 PM
I've read about intake air restrictions being used in propane conversions on the IMPCO website-  could someone please explain why that is used?
Is this because ignition timing needs to be changed with throttle position but can't be in a typical retrofit?  I can manage that electronically if I must.

I am no expert on the propane (or natural gas) conversions although I do have some experience with different systems. In the case of a diesel engine conversion for power generation, we are tuning for a fixed speed and therefore adjusting the fixed timing to best performance at that speed is easy and does not require variable timing at all. As far as air-restrictor plates go, in the typical diesel system you run with basically unlimited or excess air and vary only the fuel delivery to change engine power and/or speed. The excess air passing through does not matter too much as long as it is sufficient for combustion. In a gaseous fueled setup you are dealing with slightly different dynamics. Best power can be achieved by controlling/reducing the amount of excess air flowing through the engine. My interpretation is this: Stoichiometric mixture ratio (fuel vs air) is much more critical with Natural Gas and Propane. There is also an issue related to dropping engine vacuum if you want to idle the engine... the restrictor plate will have a big effect on this aspect. I am uncertain as to the exact correlation with pre-ignition or detonation, but do know that very precise ignition timing is key. Hardened rings, valves, and seats is also a must if you want the engine to live a long and productive life.

dieselgman
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on January 04, 2015, 01:35:08 AM
Thanks Gary.  While I sort out the propane carburetor mount/adapter and throttle linkage mods, I'll try to design in an adjustable intake restriction plate.

Is the EGT higher for a typical propane fueled engine than diesel?  I'm trying to understand the need for harder rings, valve seats, valves. 

Title: Re: DES 8/1 Propane Conversion project
Post by: dieselgman on January 04, 2015, 04:34:55 AM
Yes, your EGT and combustion chamber temps will be significantly higher with Natural Gas or LPG fuels. Unhardened parts will burn and break under the increased stresses - in particular rings/valves/valve seats.

I know from personal experience what happens to unmodified valve train components when subjected to increased stresses and temps - outright failure and disintegration.

You will be able to run stock parts for prototyping, but under full loads and normal operating conditions, your parts will fail prematurely and sometimes catastrophically.

dieselgman
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on January 04, 2015, 03:22:34 PM
Thanks, Gary.  I guess I'd better invest in an EGT sensor and gauge. 
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on January 05, 2015, 09:19:13 PM
Where could I find  hardened valves, seats for 8/1 DES head for running at a higher EGT?

I'm thinking it may be easier to have the machine shop redo the valves before the rebuild. 

Title: Re: DES 8/1 Propane Conversion project
Post by: Tom on January 05, 2015, 09:45:53 PM
My machine shop put hardened seats in the head for the 6/1. IIRC I think they for a 90 series detroit diesel.
Title: Re: DES 8/1 Propane Conversion project
Post by: buickanddeere on January 07, 2015, 12:36:12 AM
A 10HP diesel maybe only able to make 5-6HP on propane with pilot injection. With the intake restricted and the air/fuel mixture at ideal.  Best of both with maybe a 9-11 to 1 effective compression ratio with a 12-14 to 1 effective expansion ratio.  Beats reducing a diesel's compression and threading in a spark plug.
Title: Re: DES 8/1 Propane Conversion project
Post by: 38ac on January 07, 2015, 01:06:05 AM
Bruce , I install the hard seats but freight would likely kill the deal. Any local engine machine shop worthy of the name can do it for you. You will need to give them the valve head recession spec which is .005-.100. I am not a fan of the Detroit seats as they are slightly smaller than the valve heads thus the seating contact has to be real low on the valve. I can give to the Qual cast part number for the seats I use if you want it,  I can also send some out for you to give to the shop that preforms the work. 
Butch
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on January 07, 2015, 04:00:45 AM
Thanks very much Butch.  Please do send me the Qual cast part number when you get a chance.  I'll talk with the machine shop guy later this week.

What about better valves?  Any suggestions?




Title: Re: DES 8/1 Propane Conversion project
Post by: dieselgman on January 07, 2015, 05:02:04 AM
To my knowledge there are no ready-made special valves available to fit the CS. I am sure that they could be made to order by the same outfits that produce them for other engine types... costs would be prohibitive without significant volume though.

Rings are likely to be the same equation. Nodular iron is in common use for certain types, but maybe not to fit the CS.

dieselgman
Title: Re: DES 8/1 Propane Conversion project
Post by: 38ac on January 07, 2015, 12:34:57 PM
Luckily the CS uses a very popular cylinder diameter and rings are easy to source. I have been using Hastings sets #7249 which is made of modern materials.  I am not certain about compatibility with gas fuels but a call to them would sort that out promptly.  As far as I can tell by checking surface hardness the Indian valves are of the same quality as OEM and dont recall ever reading of an Indian valve failure here but again with gaseous fuels that may require something better. I have sources for stainless steel valves but they are blanks thus the stem would have to be trimmed and keeper grooves machined.
Title: Re: DES 8/1 Propane Conversion project
Post by: deeiche on January 07, 2015, 03:23:01 PM
Hey, I did a search for the Hastings rings you wrote about.  Turns out Hastings has a web page for Lister diesel, thought I'd post it for historical purposes.

HASTINGS Piston Rings - LISTER Diesel (https://www.hastingsmfg.com/RingFinderMasterDetails.aspx?AppMACD=LISTDIE%20&AppMOCD=LISTER%20Diesel&AddText=(Listed%20by%20Cylinder%20Diameter))
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on January 07, 2015, 10:53:20 PM
Thanks for the Hastings ring set number, Butch.  I'll give them a call re: propane fuel use.
Title: Re: DES 8/1 Propane Conversion project
Post by: 38ac on January 08, 2015, 12:10:50 AM
OK, Here is some valve seat info for everyone. Please  I am not bashing the shop Tom used. Obviously the DD seat will work, going a bit larger gives a person some freedom where to place the seat on the valve.

Shown is a 6/1 valve and the Detroit Diesel 5148490 seat on top of the Qual Cast 20-1562-4 that I prefer to use.
(http://oi59.tinypic.com/zu31qd.jpg)

Next is the 2 7/16 DD seat sitting on the valve. Hard to get the photo to show what I want bu the seat is smaller than the valve head. This is not terrible but causes the seat to be placed very low on the valve head, bad for flow.
(http://oi59.tinypic.com/2zyftz5.jpg)

Now the 2 9/16 QC seat I like to use
(http://oi57.tinypic.com/if5ys7.jpg)

Here installed to give .100 valve depth in a Dursley 6/1 head
(http://oi57.tinypic.com/24v30vl.jpg)

And a picture of the valve from that head. The darker ring is the placement of the seat on the valve.  A smaller seat would bring that ring toward the stem, larger seat would move it toward the margin.
 (http://oi61.tinypic.com/2vcvklg.jpg)
Title: Re: DES 8/1 Propane Conversion project
Post by: dieselgman on January 08, 2015, 12:41:00 AM
Since this thread is basically about using alternative gaseous fuels - and more specifically LPG, I have to ask, "Are stellite (hardened) seats available from Qualcast in the correct sizes?" I know that Lister used fairly soft material in their diesel valve seats and some VERY hard stuff for the Natural Gas versions... The diesel seats are a snap to re-surface, but I have found it very difficult to resurface or cut the natural gas seats even with new specialized carbide tooling because they are so hard and resistant to tool penetration.

Thanks Butch for your clear illustrations and valuable insights! Those are some beautiful mods to the original CS heads.

dieselgman
Title: Re: DES 8/1 Propane Conversion project
Post by: Tom on January 08, 2015, 12:54:34 AM
I don't know which seats my shop used, I suggested the Detroit ones, but he said he'd look in the book for the best fit. I guess I should have asked. I do know that the seat area is near the middle of the valve face. Lots of good info here on parts!
Title: Re: DES 8/1 Propane Conversion project
Post by: 38ac on January 08, 2015, 01:08:27 AM
Gary, Valve seat technology has advanced eons in the last 10-15 years. Stellite worked well and still does but is kinda old school. It is harder than hard but you cant do anything with them. Alloys that are used now allow you to work the seats after you press them in the head but work harden in use while recessing very little. Quacast has a nickle based alloy that is supposed to be the cats meow for gas fuels. Other mfgs have their own brew. I use Qual cast because they are stocked near me. Others will do same job.
Title: Re: DES 8/1 Propane Conversion project
Post by: dieselgman on January 08, 2015, 01:56:19 AM
Well, I guess I'm just an "Old School" sort of guy...  :)

Thanks for that information about nickel alloys and work-hardening... I obviously have some new research to look into.
You are the top of my list for cylinder head reconditioning resources when we can collect a large enough batch to spread the shipping costs Butch! Thankyou!

dieselgman
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on January 08, 2015, 04:35:48 AM
Many thinks, again, Butch.  The Qual Cast seats look great.
Title: Re: DES 8/1 Propane Conversion project
Post by: guest23477 on January 11, 2015, 02:41:03 AM
Hello,
I met a guy who was doing sort of the same thing, here is a link about his ignition
project of a Listeroid. I believe his goal was wood gas but he started out on LP
gas first.

Here is the link, maybe it will help you.

 http://wiki.gekgasifier.com/w/page/30448258/Spark%20conversion%20for%20Lister%20slow%20speed%20diesel%20engines

He claims he did not have to reduce the compression, but was amazed at
how much ignition advance he had to use with the large stroke ....and low
BTU value of the wood gas.

I thought it might have some value in your project.

Regards,

Les
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on January 11, 2015, 05:02:00 AM
Thanks Les, I read that report fully before embarking on the project.  While woodgas, it's certainly applicable.  Points out the need for a spark retard for starting as well.  I'll see how it works out for Propane. 

Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on January 18, 2015, 09:04:22 PM
Does anyone have a spare hollow dipper for sale or a source for one? 
Title: Re: DES 8/1 Propane Conversion project
Post by: dieselgman on January 19, 2015, 03:48:54 AM
Bill W. has made up some very nice custom hollow dippers in the past and he indicated to me that he is willing to run a batch for Forum members. It is likely preferable to compile all interested parties so he can produce just the quantity that is desired and maybe can reduce costs if he does them in batches.

I will have to handle communications for the transaction. gary@dieselgen.com

dieselgman
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on January 19, 2015, 10:39:51 PM
Gary, that's great about the dippers, I'd like to order 2 and will send you an email.
Progress report-
We got the DES 8/1 on Friday, thanks! Well packed and a lot less tippy without the cylinder and head on the case.

I've worked out a plan for the IMPCO CA55 carburetor mount- works best to use it downdraft on the intake manifold.  I can then extend the governor arm to the opposite side and use a straight push rod up to the CA55 throttle arm.  The stock air cleaner will fit the IMPCO inlet.  I just have to make a flange for a mount, will weldbond it to the intake manifold.  The IMPCO carb is very well designed, easy to switch the throttle arm from side to side as well as the idle stop limiter.

I've modified a COV plug to be a big smartplug (smartplugs.com).  Didn't like the RC shielded sparker for it's DC-DC converter emissions, will work up something using a Wells C1717 coil on plug unit, a hall effect switch and some simple analog circuitry.

More progress on the engine tear down when the weather goes bad again.



Title: Re: DES 8/1 Propane Conversion project
Post by: Tom on January 19, 2015, 11:36:49 PM
Oh boy it won't be long now. Since it won't be first smoke, what'll we call the first run on propane?
Title: Re: DES 8/1 Propane Conversion project
Post by: dieselgman on January 20, 2015, 12:27:30 AM
If it goes anything like our usual HRG builds - first backfire!

dieselgman
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on January 20, 2015, 05:52:39 AM
Smoke, backfire.  You're ahead of me but I'm working towards that! 
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on January 22, 2015, 05:45:20 PM
Talked with Tom at Central Georgia Generator about our ST3 with 240V output, AVR off of the mains instead of harmonic for better flicker reduction.  He's going to prewire it for us, which is a nice time saver.  I appreciate Tom's great service and better quality ST's as well as the price.  He's upgraded both bearings and rectifier on these, so I don't have that project to mess with.

Eaton Compressor is providing the 5hp 2 stage inline pump.  All cast iron, low speed and quiet with pneumatic unloaders and real valves, not reed. 

My friend Mark is stripping the case this weekend. He thinks we can have it hot tanked in nearby Show Low.
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on January 26, 2015, 12:17:23 AM
I'm looking for a thermostat mod/housing for the DES 8/1.  Anyone have any suggestions? 
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on January 31, 2015, 10:55:46 PM
I'm grinding the head for the thermostat, but am still looking for a flange spacer or gasket to space out the stock flange.  Cork gasket material looks like it could do it, but I don't have experience with it.
Any suggestions?

Title: Re: DES 8/1 Propane Conversion project
Post by: mike90045 on February 01, 2015, 02:01:41 AM
Quote
I'm grinding the head for the thermostat, but am still looking for a flange spacer or gasket to space out the stock flange.  Cork gasket material looks like it could do it, but I don't have experience with it.
I found a thickish gasket at NAPA parts and stuck several togther with gasket shellack and made a spacer, it's held for a year so far .  I can look up the part # tomorrow f you need it,
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on February 01, 2015, 05:27:04 PM
If you get a chance, Mike, I would like to have that NAPA part number.
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on February 02, 2015, 04:51:33 AM
My friend Mark put in 4 hours with a needle scaler and die grinder inside the stripped down crankcase yesterday.  He's just got a bit more work to do in the lower sump, which he needs an angle die grinder for.   This crankcase interior was very rough with sharp bits protruding and badly needed grinding. It did finish up nicely.  It will get a coat of glyptol type red electrical varnish (thanks 38ac).   The machined parts of the case look quite good and the casting looks sound.

It's quite a change from my Metro Listeroid; this is a true CS clone with the oil pump, upper and lower sump, 7 bolt head, one piece cylinder (no sleeve) and bushed mains.  I'm ambivalent on the clone vs listeroid choice, but I am glad to not have to deal with the inevitable liner protrusion.

The head is flat overall though somewhat wavy, and I think I'll put it on my sandpaper/plate glass and see how it looks.

I'll be uncrating Jeff's new ST-3 from Central Georgia Generator tomorrow.  Tom at CGG has upgraded the bearings and bridge diode on these, so I'll only have to add 4 EMI suppression capacitors on the bridge.

Title: Re: DES 8/1 Propane Conversion project
Post by: mike90045 on February 02, 2015, 08:42:59 PM
Quote
I'm grinding the head for the thermostat, but am still looking for a flange spacer or gasket to space out the stock flange.  Cork gasket material looks like it could do it, but I don't have experience with it.
I found a thickish gasket at NAPA parts and stuck several togther with gasket shellack and made a spacer, it's held for a year so far .  I can look up the part # tomorrow f you need it,

NAPA 1038-ST
  is a gasket that fit my metro water outlet.  I stacked several of them to make a spacer, which I needed even after grinding the head outlet & the housing cover.
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on February 03, 2015, 01:42:25 AM
Thanks, Mike!
Title: Re: DES 8/1 Propane Conversion project
Post by: buickanddeere on February 03, 2015, 03:24:23 AM
  I was just thinking. If operating a diesel engine on just diesel for pilot ignition and only LP for the primary fuel. If the cam was retarded a tooth or two, the intake valve would close late and allow some of the AF mixture to be pushed back into the intake manifold. This would lower the effective compression ratio and reduce the tendency for detonation.
  It would be worth tinkering with on a slow afternoon.
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on February 03, 2015, 04:17:38 PM
What timing changes would be best for propane is an interesting idea.  I'm hoping that due to the slow speed, it won't be critical.
Title: Re: DES 8/1 Propane Conversion project
Post by: dieselgman on February 03, 2015, 04:48:03 PM
For spark ignition N.G. Listers, in the variable speed range of 1200 to 2200rpm, ignition timing is quite critical. I suspect that if you were using diesel as the pilot fuel, and using compression ignition rather than spark, that it would substantially change the combustion dynamics. It will be quite interesting to see what kind of results are obtained from this project/experiment.

dieselgman
Title: Re: DES 8/1 Propane Conversion project
Post by: 38ac on February 06, 2015, 01:37:16 PM
Have you any idea how  much "a tooth or two" actually changes ignition timing?  I can see problems with mixture and fuel consumption here.
 Of course then there is the question of how that is going to effect the exhaust valve timing in the cycle and what that is going to do.
It would be a surprise if the engine ran at all 2 teeth out.

I have zero experience with all of this but wondered along those lines myself.  What is the difference between the pressure needed to ignite the diesel fuel and the pressure which causes LP to detonate?  40 years ago there were kits sold for farm tractors that injected propane into the intake as a power adder for heavy work. There was no real regulation of the LP, just a constant stream that was on or off  but the primary fuel was diesel and the percentage pf propane was small.
Title: Re: DES 8/1 Propane Conversion project
Post by: dieselgman on February 06, 2015, 02:10:17 PM
Pre-ignition is the enemy and can hammer a good engine to pieces pretty quickly - or at least make a nasty hole in your piston and ruin your day. With spark ignition, the adjustment can be easily made for varying conditions of speed and loading to avoid getting into an engine destroying condition.

Compression ignition in the diesel relies on the timing of the fuel pulse... not simply reaching the flash-point temperature in the chamber.

Both of the above are very precise and fussy adjustments and have quite large influences on the power output, longevity, and efficiency of your engine.

We know from previous experience that propane will operate fine as supplemental fuel in a diesel engine - where the diesel fuel (compression ignition) is providing the primary timing pulse because it is providing the entire ignition source.

Now, if you are going to switch over to propane (or natural gas - methane) fuel and run without the diesel, you will need to add a spark ignition and also drop the compression ratio at least to a point where the fuel does not pre-ignite in the cylinder (before the spark is applied). Engine manufacturers (including Lister/Petter) have already performed many of these experiments and given us some base-lines to refer to.

I think we are primarily lacking good experimental data for a slow-speed situation such as what the CS presents...
Some things to think about.

dieselgman
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on February 07, 2015, 12:09:02 AM
Hopefully the low, fixed rpm will make valve timing issues non-critical.  I can do whatever is needed re: dynamic spark timing adjustment if I have to go spark.  I'm hoping the Smartplug (smartplugs.com)  I made in a spare COV plug will work as well with propane as the last conversion (alcohol fuel) I did with it. It was a 4 cycle outboard, and it worked well at any speed and had decent acceleration.

The crankcase is done and painted, and Mark says he'll bring it out for me to start on it Monday.  We've both got several other projects going in building my new neighbor's home and off grid power system.



Title: Re: DES 8/1 Propane Conversion project
Post by: buickanddeere on February 07, 2015, 06:48:29 PM
  I was just thinking. If operating a diesel engine on just diesel for pilot ignition and only LP for the primary fuel. If the cam was retarded a tooth or two, the intake valve would close late and allow some of the AF mixture to be pushed back into the intake manifold. This would lower the effective compression ratio and reduce the tendency for detonation.
  It would be worth tinkering with on a slow afternoon.

Have you any idea how  much "a tooth or two" actually changes ignition timing?  I can see problems with mixture and fuel consumption here.
 Of course then there is the question of how that is going to effect the exhaust valve timing in the cycle and what that is going to do.
It would be a surprise if the engine ran at all 2 teeth out.

The idea is to limit combustion chamber fill and the effective compression ratio to prevent pre-ignition with the "low" octane LP fuel. Rather than restricting inlet airflow with an orifice which only works at a single rpm and load.
   There should be enough adjustment on the injection pump lobe to keep the injection event occurring at 15 or so degree BTC ? 
   Considering the care and accuracy how the cam lobes are hammered onto the cam shaft in India.  Intake and exhaust timing is already all over the map.
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on February 16, 2015, 12:58:47 AM
Some photos of the COV plug converted into a primative smartplug using an RC glow plug (see smartplugs.com).  Think of hot tube ignition only with a platinum element glowing instead of heating the pipe.  Timing is adjusted by the length of the chamber after the glow plug.  In my version the timing is controlled by the length of a bolt threaded into the post plug cavity.  I've used this method before successfully in a Honda 2HP 4 cycle outboard.

https://drive.google.com/open?id=0B-wQ0EwBmioQYUF6cVk3bEtVaWc&authuser=0

https://drive.google.com/open?id=0B-wQ0EwBmioQQ2paalBmaFJQOGs&authuser=0

And a photo of my spark plug adapter. It's just 1/2" black pipe with a threaded bushing to fit the injector hold down.  I don't know how it will hold up over time but the fit is pretty good. The spark plug boot had to be sanded down a bit and then silicone grease is a must.  

https://drive.google.com/open?id=0B-wQ0EwBmioQVkpLTjZ4cXNQWlU&authuser=0

I also checked the connecting rod and wrist pin today. 0.0025 clearance, nice quality machining on the wrist pin.  Piston is also very nicely made.
The big end is 2.005" with  shims still in place from the factory, which is right in the ballpark. Same on each side, also encouraging.  I haven't gotten the case and crank back from Mark as he's been busy on the building project.  I want to get the camshaft in my hands next.

Bruce





Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on February 17, 2015, 04:23:21 AM
Got the crankcase and most of the parts today except flywheels and tappets. The crankcase looks great on the inside now, I love the smooth red electrical varnish finish.

Cam had 0.008" of runout on my new hardwood V blocks but was easily remedied, now within 0.0015. (Thanks 38ac!)  Top deck is 0.005 out on initial check via 38ac's method, not bad. I"ll recheck after everything is tightened. 

The crankshaft on V blocks seems to have a little runout (0.002") but I need to recheck that with 38ac's method now that the crank is in the case. 

Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on February 26, 2015, 03:53:59 PM
I'd love some advice on how valve timing should be adjusted for better propane operation at 786 rpm.
Are intake open and exhaust close still the top priority? 
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on February 27, 2015, 12:18:55 AM
The intake valve cam profile is interesting on this engine.  Long, VERY early ramp up to about 0.0020 open.   With 0.039 lash, the timing is perfect and valve lift is brisk.  The exhaust closing is perfect at 0.040 lash.   I'm very happy with 38ac's timing methods!

I'll start with the stock diesel timing for intake open and exhaust close unless someone suggests otherwise.


Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on February 28, 2015, 01:42:23 AM
Making some good progress today,  made some stands and balanced and matched the flywheels per 38ac's method. Fast and easy and should save a lot of time on fine balance. I did not drill, I added lead to the rim, first to get the counterweight lined up opposite the shaft key for both, then measured the counterweights with a can of lead shot and added a few oz to the lighter counterweight.  I got the 12"x2" rod at Amazon.

(http://i1119.photobucket.com/albums/k626/rbmccreary/DSCN0231_zpsxyliycud.jpg) (http://s1119.photobucket.com/user/rbmccreary/media/DSCN0231_zpsxyliycud.jpg.html)

Ready to mount the propane carb and make a new governor linkage to operate the new throttle.  Still scratching my head about how to fix the rocker arm- the exhaust valve is 3/16" too far away. I need a rocker arm stretcher, I guess. You can see the Gast 4AM rubber roller starter still needs a frame and cylinder actuator.

(http://i1119.photobucket.com/albums/k626/rbmccreary/DSCN0234_zpsjsup3inm.jpg) (http://s1119.photobucket.com/user/rbmccreary/media/DSCN0234_zpsjsup3inm.jpg.html)

Here's my Smartplug modified COV plug installed. The slotted screw will be adjusted in length to change ignition timing.  

(http://i1119.photobucket.com/albums/k626/rbmccreary/DSCN0235_zpsd5vsxk57.jpg) (http://s1119.photobucket.com/user/rbmccreary/media/DSCN0235_zpsd5vsxk57.jpg.html)



Title: Re: DES 8/1 Propane Conversion project
Post by: dkeav04 on February 28, 2015, 02:33:53 AM
Coming along nicely, every so patiently waiting for that first run video  :laugh:
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on February 28, 2015, 05:51:07 AM
Propane carb adjustments, a rather arbitrary compression setting (0.090 shim) and my homemade smart plug/cov plug  for ignition will likely make for a bit of a project to get her starting and running adequately.  Fingers crossed for later next week. 
Title: Re: DES 8/1 Propane Conversion project
Post by: Tom on February 28, 2015, 10:34:41 PM
Anxiously waiting for that first run here. Looks great Bruce.
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on March 16, 2015, 07:22:47 PM
First smoke achieved on the homebrew smartplug on the first attempt, though there was no smoke since it was propane fuel. It ran with the carb as delivered, though as soon as it warms up it does start missing.  As it warms up more it misses more until it won't stay running.  

[youtube] vDbqAsVB52Q[/youtube]

Carb adjustment of the Impco CA55-576  has been a study in frustration.  Neither idle adjust nor main fuel mix has any effect!  Neither does covering much of the intake opening or the balance adjust screw.  I'm utterly baffled.  Suggestions would be welcomed.

Until I can figure out a plan on the carburetor I'm working on hooking up the air compressor for a load, and working on hooking up the spark system.  The diy smartplug won't stay hot enough to run without 2 amps of 1.5v, and I'm reluctant to re-engineer a more sophisticated plug.  Mark Cherry has dropped the smartplugs and they are unavailable.

Title: Re: DES 8/1 Propane Conversion project
Post by: veggie on March 16, 2015, 08:26:02 PM

BruceM,

That's excellent !
Nice work !
From concept to running engine in just a few months.

...And thanks for documenting your work along the way. Make this forum soooo useful.


Cheers,
Veggie
Title: Re: DES 8/1 Propane Conversion project
Post by: buickanddeere on March 16, 2015, 08:34:36 PM
First smoke achieved on the homebrew smartplug on the first attempt, though there was no smoke since it was propane fuel. It ran with the carb as delivered, though as soon as it warms up it does start missing.  As it warms up more it misses more until it won't stay running.  

[youtube] vDbqAsVB52Q[/youtube]

Carb adjustment of the Impco CA55-576  has been a study in frustration.  Neither idle adjust nor main fuel mix has any effect!  Neither does covering much of the intake opening or the balance adjust screw.  I'm utterly baffled.  Suggestions would be welcomed.

Until I can figure out a plan on the carburetor I'm working on hooking up the air compressor for a load, and working on hooking up the spark system.  The diy smartplug won't stay hot enough to run without 2 amps of 1.5v, and I'm reluctant to re-engineer a more sophisticated plug.  Mark Cherry has dropped the smartplugs and they are unavailable.



Try tweaking the LP gas pressure from the regulator prior to the 'carb".
Title: Re: DES 8/1 Propane Conversion project
Post by: dieselgman on March 16, 2015, 09:02:05 PM
Try this on...

Problem:
I can get the engine to run at one speed and load okay, but it won't run right if I try to speed it up or slow it down.

Solution:
This is probably caused by the idle screw being open too far, and the load screw turned in too far. This wrong combination will run the engine at one speed and load. You should close off the idle screw completely, open the main load and get the engine running okay at governed speed. Slowly reduce the speed and as the engine tends to run a little rough, open the idle needle screw just enough to make it run smoothly. Keep working the speed down and keep the idle needle screw adjusted until you reach the desired idle speed.

Problem:
My engine was idling too fast so I closed down on the idle mixture screw to reduce the speed but it runs rough.

Solution:
Never attempt to control idle speed with the idle mixture. Idle speed should be controlled with the idle stop screw near the governor. This adjustment controls the throttle butterfly valve opening at idle and in turn the idle air flow. At that air flow, always set the gas idle mixture screw for fastest speed.

Problem:
Engine runs but won't come up to full speed or power.

Solution:
In most cases poor power is caused by a mixture that is too lean. This lean mixture is often caused by too many pressure regulators in the system or some small or restrictive fitting causing poor flow. Almost all conversion kits are designed so that the engine will lose power if the load adjusting screw is opened too far.

Question:
I have a vapor withdrawal kit and the engine runs fine for a while and then frost starts to form on the regulator. Is it possible the vapor pressure reduction and flow is causing this?

Answer:
No. Frost is always caused by drawing liquid from the tank. Your tank may be over filled or oriented wrong.

Problem:
Engine won't start or is hard to start.

Solution:
More starting problems are caused by over priming or dirt on one of the regulating seats causing gas to leak through. If propane or natural gas make up more than 10% of the fuel air charge, the spark plug will not ignite the mixture, it is too rich. Propane and natural gas require from 50% to 100% higher temperature to ignite a charge as compared to gasoline. The ignition must be in good shape. You might try changing the spark plug gap to around .025

Starting Problems:
Starting has never been a serious problem when dealing with single fuel alternate fuel engines. However, with dual fuel applications, especially those under 250 cid, there are many factors that can contribute to hard starting. These are:
1. Vacuum and air leaks
 2. Incorrect carburetor sizing
 3. Improper idle mixture adjustment
 4. Over richening by start assist valve
 5. Incorrect location of carburetor, regulator and or fuel lock
 6. Improper location of electric fuel lock head
 7. Incorrect spark plug gap
 8. Cold ambient air temperatures
 9. Incorrect starting technique
 10. Poor engine condition

Vacuum and Air Leaks
In dual fuel applications on small displacement engines, an air leak, which would not bother a larger engine, becomes critical, especially at cranking speed. Any leak downstream of the air gas valve will reduce the amount the valve will rise off its seat during cranking.
 In extreme conditions, air enters through the leak during the entire stroke, while the gas valve is lifted only during part of the stroke. This creates a mixture too lean to burn. A primer may furnish the added fuel around the metering valve to allow the engine to start, and with more numerous intake cycles the leak may be overcome.
 Vacuum leaks may be detected by spraying gasket sealed surfaces with a soapy solution. If a leak is located, the engine will speed up due to the richer mixture. This technique is quite effective around the gasoline carburetor area. Air leaks may also be found in the engine, through intake valve seals or past rings, which are not seated. The orifice in the PCV valve, which is open during cranking and closed under vacuum, can add a sizeable amount of air. Be sure the PCV valve does close properly after the engine starts.

Carburetor Sizing
It is important to correctly size the air flow capacity of the mixer to the engine requirement. Use of a mixer that is too large for the engine displacement makes idle adjustment extremely sensitive. When the larger mixers are applied to smaller engines, enrichment for acceleration or power occurs too high in the RPM range to be practical. The small engine cannot lift the large air valve quickly or as high as a larger engine will.

Idle Mixture Adjustment
Correct idle mixture adjustment is critical to ease of starting. This is compounded if the mixer is over sized for the engine. When the idle mixture (air bypass) adjustment is closed, the air valve will open farther at cranking. Thus, the air flow volume remains the same but gas flow is increased.
 If the engine starts hard, check the idle mixture adjustment, following this procedure: Tighten the idle mixture screw in. If the engine starts more easily, slow the engine down while adjusting the idle mixture to prevent stalling from an over rich mixture. Setting the idle mixture to the best idle (high vacuum) cold will give a reasonable lean but satisfactory mixture after the engine warms, however it should be adjusted to specifications in the fuel mixture adjustment section.

Start Valve Enrichment
Use of the SV start assist valve for priming during cranking is helpful. However, on engines two liters and under, a restriction such as the Impco J1-20 (1/16" I.D.) should be used. If these are not available, a spark plug nut, approximately 1/16" I.D. pushed into the hose will prevent over priming.
 The sizing of the orifice to the engine can be checked for accuracy by energizing the SV valve separate from the starting circuit. When activated with the engine idling, it may slow the speed or actually kill the engine. However, if by opening the throttle it will start in a turn or two, the orifice is satisfactory.
 The SV should always connect to the air valve vacuum, not the intake manifold

Location of Components
Mounting the converter and fuel lock off the engine is desirable when carbureting 4 cylinder engines. The vibration of the engine moves the converter rapidly back and forth while the secondary diaphragm assembly tends to stay still. This causes the gas pressure to pulse, and can cause excess fuel consumption. The added weight of an LPG mixer and adapter on a gasoline carburetor, if not properly braced, can combine with the vibration of a 4 cylinder engine to cause the gasoline carburetor fasteners to loosen, creating air leaks.

Electric Fuel Lock Connection
Attaching the electric fuel lock vacuum switch power lead to an ignition coil terminal often leads to starting difficulties. The coil terminal is a weak source of current, and having the fuel lock's power lead attached to it robs the ignition system of needed amperage.

Incorrect Spark Plug Gap
Spark plugs should be in good condition and gapped to factory specs. A protruded nose plug is helpful if it will clear the piston at the top of its stroke. On smaller engines a .025 gap is usually helpful

Ambient Temperatures
At very cold ambient temperatures -30 F -34 C or below, there may be insufficient vapor pressure in the fuel tank to supply fuel to the converter / regulator, resulting in no start or hard starting. Another condition, which may prevent starting in cold weather, involves over priming. If this condition is suspected, attempt to start the engine with the primer disconnected. The primer can be disconnected by removing the electrical connector or by pinching the fuel hose.

Incorrect Starting Technique
Over cranking the engine, especially in cold weather, causes over priming and flooding, a common starting problem.
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on March 16, 2015, 09:29:28 PM
Thanks, Veggie, Gary and Buick&Deere.

I had read that article you referenced, Gary. Alas, NO adjustment makes ANY change at all.  Imco seems to provide virtually nothing, so I searched the web trying to find CA55 adjustment tips.

I'll hook up a pressure gauge and see what the new BBQ regulator is up to. Should be about 10" of water pressure.

Raising compression reduced the missing significantly. I did that in part to see if my DIY smartplug would then stay hot enough without applying battery current. Alas, no.  Mark Cherry's advanced prototypes for gas and propane fuels used much more platinum wire, with more direct surface contact.  Some did require current to run.

The engine starts immediately as soon as fuel and compression are applied and will run nicely for a while before missing. It will start missing fairly quickly if it's a warm day.


Title: Re: DES 8/1 Propane Conversion project
Post by: 32 coupe on March 16, 2015, 10:22:27 PM
I'm gonna go out on a limb here...........
runs good till warms up.....
valve lash ?





Title: Re: DES 8/1 Propane Conversion project
Post by: George A on March 16, 2015, 10:22:38 PM
Starts missing on a warm day? Is the outside of your propane cylinder icy and frosty? If so, the fuel is being drawn out too quickly and it's trying to be delivered as a liquid instead of a vapor, which will "flood" the engine. This same condition can also cause a blockage of the fuel line, which gives the same symptoms. The answer is usually a tank and/or regulator with more capacity I believe.

Either that, or the engine is pulling more gas than the regulator can deliver. If there's a forklift dealer in your area, why not ask them what they do with a propane fuel system that acts up?
Title: Re: DES 8/1 Propane Conversion project
Post by: Tom on March 17, 2015, 01:26:40 AM
Perhaps that 20 lb LP tank is to small to make enough vapor for that engine. Does it get cold?
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on March 17, 2015, 03:09:37 PM
Good thoughts, guys.  The engine is not pulling a load, yet, so fuel demand should be minimal, but I'll check the tank temp today.
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on March 17, 2015, 05:09:55 PM
Tank and hose aren't getting cold, today the missing starts almost immediately.  I'll see if it goes away with the spark system.
Title: Re: DES 8/1 Propane Conversion project
Post by: George A on March 17, 2015, 07:57:10 PM
Just another thought Bruce..........have you disconnected the propane line then turned on the tank valve and just let the gas come out? It could be that the regulator is goofed up inside and only works intermittently.
Title: Re: DES 8/1 Propane Conversion project
Post by: carlb23 on March 17, 2015, 09:03:44 PM
You would think that a regular barbeque tank should easily provide enough flow to run the 6/1 especially unloaded.  Most 4 burner gas grills are 48,000 Btu's and the tank doesn't normally freeze. If diesel is aprox 130,000 BTU's per gallon and a loaded 6/1 uses aprox 1/3 gallon per hour then even loaded it should only be needing aprox 43,000 BTU's.   That being said as mentioned above you may have a bad regulator.

Just my 2 cents

Carl
Title: Re: DES 8/1 Propane Conversion project
Post by: broncodriver99 on March 18, 2015, 12:18:32 AM
Newer propane tanks have flow limiting devices built in. I have had a couple that were especially finicky that I had to slowly open the valve on or they would trip and shut off. It may have something to do with it. Another avenue to venture down anyway. Do you have an older or different tank you can try?
Title: Re: DES 8/1 Propane Conversion project
Post by: buickanddeere on March 18, 2015, 12:48:21 AM
After readinthe article. I'm thinking the LP carb/mixer/regulator are too large .
Title: Re: DES 8/1 Propane Conversion project
Post by: 38ac on March 18, 2015, 03:59:05 PM
My only experience with propane is with a hit miss engine and hot tube ignition. Mixture is critical with that one and the only way the tank with shut off valve will work is with a surge tank between the engine and the LP tank, otherwise the call for fuel would cause the shut off to activate . I suggest a gauge in the line as a first step so you know what is going on there.
Title: Re: DES 8/1 Propane Conversion project
Post by: 32 coupe on March 18, 2015, 04:53:17 PM
I second the gauge idea.
How do you know what it's doing without one ?
I'm just say'n. ..


Gary



Title: Re: DES 8/1 Propane Conversion project
Post by: Tom on March 18, 2015, 07:03:17 PM
Just ran into this at the fire department. We made an LP burner in the bottom portion of a 55 gal barrel filled with water. It's used for fire extinguisher training and they could not get enough flame. I found that the bottle adapter used had a restriction in it. After drilling it out we had flames 8' high.  :police:
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on March 19, 2015, 03:57:04 AM
Thanks for the good ideas, guys.  The CA55 carb is rated for a big range of engines  but a Listeroid is in the range.  What bothers me most is that the idle and rich/lean main adjustments don't seem to make any difference in running at all. A gas line pressure gauge is needed to see what's going on and I'll get one ordered tonight.

I got the hall effect/spark circuit bread-boarded and tested this AM, hopefully will get it on the engine over the next few days.  I'm going to try fixed timing off of the former injection pump cam-bolt with a magnet on top, hall effect switch epoxied to an aluminum plate where the injector isn't.  Injector cam-bolt can then be adjusted to dial in spark timing. A 555 IC provides a 4ms pulse to a Mosfet to charge the coil and discharge it.  I may have to add some circuitry to retard timing for starting if that proves a problem.

Big rush on getting a roof over my new neighbor's head as he's got to be camping here on the first of April.





Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on March 19, 2015, 05:06:11 AM
Impco is pretty lousy on documentation, but I did find that some of their carbs are designed for 5" of WC regulators. I'm thinking perhaps the BBQ pressure regulator is a bit too high for it.  Another document mentioned that the fuel rich/lean has little effect at idle/light loads.  No luck in finding an adjustable pressure BBQ regulator so far, but perhaps I can find a high (10-20 psi) then adjustable  low (5-11 inches WC) regulator.
Title: Re: DES 8/1 Propane Conversion project
Post by: carlb23 on March 19, 2015, 02:44:19 PM
something like this?

http://www.ebay.com/itm/Adjustable-Propane-Gas-Regulator-BBQ-Grill-Burner-Wok-Fryer-with-4ft-Hose-20PSI-/161439781888?pt=LH_DefaultDomain_0&hash=item25968f9400
Title: Re: DES 8/1 Propane Conversion project
Post by: Thob on March 19, 2015, 09:07:49 PM
Here's one that's adjustable.  It doesn't say it is, but you unscrew the blue plug and there's an adjustment screw underneath.

http://www.amazon.com/Camco-59333-Horizontal-Propane-Regulator/dp/B0024E6TX2/ref=sr_1_1?ie=UTF8&qid=1426798850&sr=8-1&keywords=camco+horizontal+two+stage+propane+regulator (http://www.amazon.com/Camco-59333-Horizontal-Propane-Regulator/dp/B0024E6TX2/ref=sr_1_1?ie=UTF8&qid=1426798850&sr=8-1&keywords=camco+horizontal+two+stage+propane+regulator)

The easy way to measure pressure on one of these is to put the outlet hose in a bucket of water.  Whatever depth it takes to just flow propane can be measured as the setting in inches WC.  Typically the Impco carbs are going to expect 11 inches WC, which is what the regulators are normally set for.
Title: Re: DES 8/1 Propane Conversion project
Post by: 32 coupe on March 19, 2015, 09:39:46 PM
Bruce,
After spending some time thinking about this, I think the spark plug
and your homebrew ignition system will cure your woes.
I would not worry about any advance/retard system. I just
don't think it will be necessary.

You do.know.the RC plugs com in different heat ranges ? I played
with rc planes for years and learned this early on after a few
tuning problems.

I'll amble off now,
Gary





Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on March 19, 2015, 10:17:26 PM
Raining now but I was able to open up the BBQ LP regulator and can now adjust it.  Thob's simple water bucket calibration method I can do while waiting for the pressure gauge to come on Monday. (Thanks, Thob.) I will place the pressure gauge right at the carburetor so there will no more mystery on that issue.

I am suspicious of my homebrew smartplug, and will report back on how the spark via coil and injection pump cam/bolt sensor works out.  I have both installed, so can easily run and switch back and forth.  I've got to solder up and heatsink the mosfet which switches the coil current since the coil draws up to 6.5 amps for the 4 milliseconds just before the spark.

I wanted to publicly thank 32 coupe for the very nice offset idler bolt he contributed for this project.  She's in good running shape re: gear lash now, from 0.013 to about 0.004" as measured with the music wire on idler tooth to dial gauge method.  I think his offset sleeve on turned down bolt method is great for moderate offsets since you could try several offsets to get it just right.  I'm not sure what the practical  limit might be, perhaps 0.030?

I'm very grateful for the helpful and encouraging project support I've received here!

Bruce








Title: Re: DES 8/1 Propane Conversion project
Post by: mike90045 on March 20, 2015, 04:44:11 PM
You may have sized your carb for a  4 cyl 1600CC, 4000rpm engine, but will it work properly for the long delay between intake "gulps" on a 700 rpm?   It's bleeding propane into the manifold while nothing is happening, then a big intake pulse comes along, can it support a quick huge draw of mixture then cease while waiting for the next?
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on March 20, 2015, 04:56:38 PM
Good points, Mike.

Since the size range is so large, and the gas metering is by diaphram/ intake vacuum, I think the IMPCO CA55 should work OK at my 786 rpm.  It does not release gas when there is no intake vacuum.  It also handles large engines at idle, so I there is a match there, sorta.  It starts  immediately and sounds fine until it starts missing, so hopefully it's something simple.

Title: Re: DES 8/1 Propane Conversion project
Post by: Tom on March 20, 2015, 07:51:31 PM
Bruce, some where back in time we discussed using a regular spark plug in the injector hole. It looks like a piece of cake to make that conversion and just use a regular plain old boring automotive coil with a set of points triggering off the IP cam follower. Kohler or Wisconsin parts would work just fine and be easily replaceable with off the shelf parts.
Title: Re: DES 8/1 Propane Conversion project
Post by: Thob on March 20, 2015, 08:17:40 PM
Raining now but I was able to open up the BBQ LP regulator and can now adjust it.  Thob's simple water bucket calibration method I can do while waiting for the pressure gauge to come on Monday. (Thanks, Thob.) I will place the pressure gauge right at the carburetor so there will no more mystery on that issue.


You're welcome.  But I have to give credit for that idea to ReedEngine over on the oilfield engine forum on smokstak for that idea.

After you've got a good ignition system working, if you're still having problems you may want to look at a different Impco carb.  From the catalog:

"The Model 110 carburetor/mixer is designed primarily for one and two cylinder engines where severe intake
manifold pressure pulsations are present."

I suspect that fixing the ignition will get it running quite well, but wanted to mention this just in case.
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on March 20, 2015, 08:50:57 PM
Hi Tom,
You remembered correctly. Earlier in the thread you'll see my picture of the spark plug replacement for the diesel fuel injector.  Points certainly could be used but I'm using a hall effect sensor with a tiny magnet on top of the IP cam follower. It is simpler mechanically, since coil dwell does not have to be incorporated into the cam.  A simple 555 circuit triggered by the hall effect sensor turns on the coil for an adjustable dwell of about 4 msecs.  That charges the conventional 12v ignition coil and it sparks when the current is stopped and the magnetic field collapses.

At the target 786 rpm, it's 76.3 ms per revolution.  To allow a 4 msec dwell,  the spark trigger must occur at 19 degrees advanced, plus whatever advance is desired.  Propane has a fast flame front, so I'll start at 19(dwell) +10 degrees= 29 degrees BTDC.

The smart plug required a minimal chamber beyond the glow plug (least possible advance).  I'll learn from that lesson.

Thanks for the carb tip, Thob.  I'll take a look at the model 110.

  



 

Title: Re: DES 8/1 Propane Conversion project
Post by: dieselgman on March 20, 2015, 09:09:14 PM
We use the Impco 110 model in updraft configuration for our HR engines in 2 and 3 cylinder versions. Parts are readily available and they adjust and run without much fuss IF the electrical side of the equation is in very good order. One backfire is all it takes to blow out the diaphragm though, and that can get to be an expensive pain in the neck while tuning - on occasion.

dieselgman
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on March 21, 2015, 08:48:58 PM
Checked the propane BBQ regular in a 5 gallon bucket- huge flow at 13" deep.  Adjusted for minimum pressure (screw all the way in), still more than 13".  So for starters, the regulator must be replaced.

Title: Re: DES 8/1 Propane Conversion project
Post by: Thob on March 21, 2015, 10:36:42 PM
I thought that running the screw out would be lower pressure???  Did you try the other way?
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on March 21, 2015, 10:55:25 PM
Thob, yes, it bellows out gas with the screw out, all the way in it's a smaller stream in the bucket.  I've ordered the adjustable 2 stage regulator you recommended.  

Got the spark timing working on the engine.  

I reduced the 555 produced dwell time to 2.5 msecs.  I can't see any difference in the spark quality there, much shorter and the spark gets weak.

I'm going to make a temporary mount for the coil now so I can give sparks a try.

I forgot to mention that yes, 38 coupe,  I'm very familiar with RC glow plugs and am using a hot plug. I was also once an RC airplane fan.   Propane just doesn't seem to react with the platinum much. Mark Cherry ( smartplugs.com ) solved this by increasing the platinum area and forcing fuel mix over the platinum surface.  I know in some fuel applications (maybe propane?) he had to provide constant current to the smartplugs for running, and changed that current to affect timing.   I don't have the time or budget for re-doing his development work, and he's to busy to return my call.  I tried varying the glow plug current in my DIY smartplug , and it made no difference in the missing problem, which I think now is just a bad propane regulator.

I haven't forgotten 38AC's comment about providing a low pressure reservoir for the intake fuel, either.  Regulators may have trouble with a pulsing input and smoothing out that demand might be helpful.  









 



Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on March 22, 2015, 01:43:14 AM
I noticed a timing problem on the IP cam follower when I was timing my magnet/hall effect spark setup.  I just checked it carefully again; my IP cam is centered on 17 degrees ATDC.   That's not a typo, the cam high spot is 17 degrees after top dead center.  My question is: will this prevent diesel operation with the IP?

Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on March 23, 2015, 01:12:24 AM
Ran it on the breadboard spark circuitry today.  No change from my DIY smart plug, runs nice, then starts missing after a minute or two, then almost stops.  I found I can bring it back to life by nearly closing the carb.   New regulator and fuel pressure gauge next, early this week.

I had to retard the spark timing via the IP cam follower bolt to near 0 BTDC to avoid knocking.  Propane doesn't need much advance!   



Title: Re: DES 8/1 Propane Conversion project
Post by: buickanddeere on March 23, 2015, 01:57:45 AM
 A MSD multiple spark box maybe a consideration ? http://www.msdignition.com/Products/Ignitions/Daily_Driver/5520_-_Street_Fire_Ignition.aspx
Title: Re: DES 8/1 Propane Conversion project
Post by: dieselgman on March 23, 2015, 02:07:41 AM
If choking or closing the carb "brings it back to life", it sounds a little like the carb dashpot is not properly responding to your normal engine vacuum - at least not until the vacuum spikes. A cracked or deformed diaphragm might produce this kind of symptom. For interest in what the cause and effect of the situation is, it might be valuable to also have a vacuum gauge on your inlet manifold during testing and adjustments.

At any rate, I would not rule out a defective or malfunctioning carburetor from what I have read of your situation. Impco makes an excellent device, but it has its inherent weaknesses and can be very finicky when something is just a little off spec.
If you wanted to do some trials or experiments with 110s, I would be willing to supply them for you gratis. Just document and share your results here.

dieselgman
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on March 23, 2015, 02:53:49 PM
Gary, thanks, a CA110 carb would answer a lot of questions, that's very generous! I'm happy to share my work, and grateful for the support from you and the forum.  I'll email you.

Buick&Deere- thanks for the link. I think multi spark has it's place, for slow burning fuels.  The smart plug is a plasma torch and can even light off 50% water/alcohol; I doubted it just because it was new (for me) to this propane fueled application.  Since (single) spark has not changed the missing, I'm proceeding with the theory that I've got a carb/regulator/fuel mix issue. 

 For both the smartplug and the spark, I've had to eliminate advanced ignition timing due to very pronounced knock.  I read that propane is a fast flame front fuel; now I'm a believer.




Title: Re: DES 8/1 Propane Conversion project
Post by: 32 coupe on March 23, 2015, 11:00:12 PM
Just thinking out loud.....
Has this been done before ? Will this type engine work with this type catb ?



I was thinking about a newer type electronic injector and one of Bruces homebrew
timer to set the ignition timing as well as a open/close timer for injector.
 
Is this sort of thinking even plausible or is my thinking just plain crazy ?

Gary

Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on March 24, 2015, 02:59:30 AM
A propane carb seems more my speed, but it would be interesting to see what else is being done with propane fueled engines. 




Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on March 24, 2015, 04:48:29 AM
(https://lh4.googleusercontent.com/-6wvJuvd8XDI/VRD0NpXqqoI/AAAAAAAAAQg/NLj67CkMb8c/w428-h570-no/DSCN0236.JPG)

Here's my fugly jury rig for the spark system. The hall effect sensor is presently just taped to an aluminum plate mounted on the IP location.   The magnet self adheres to the IP cam follower/bolt head. I'll epoxy both magnet and sensor in place later.  An 8 pin 555 timer chip triggers from the low going hall sensor, turns on the coil through an N-channel MOSFET for 2.5 msecs, then shuts it off which makes a spark.  The solderless breadboard is being used until I'm sure I won't need more features such as retarded timing for starting.

The whole spark system will be in a shielded enclosure when I'm done.



Title: Re: DES 8/1 Propane Conversion project
Post by: buickanddeere on March 24, 2015, 10:31:17 PM
Gary, thanks, a CA110 carb would answer a lot of questions, that's very generous! I'm happy to share my work, and grateful for the support from you and the forum.  I'll email you.

Buick&Deere- thanks for the link. I think multi spark has it's place, for slow burning fuels.  The smart plug is a plasma torch and can even light off 50% water/alcohol; I doubted it just because it was new (for me) to this propane fueled application.  Since (single) spark has not changed the missing, I'm proceeding with the theory that I've got a carb/regulator/fuel mix issue. 

 For both the smartplug and the spark, I've had to eliminate advanced ignition timing due to very pronounced knock.  I read that propane is a fast flame front fuel; now I'm a believer.

 LP is going to knock with the diesel compression ratio as the octane is too low. Unless you restrict the air/fuel flow so the cylinder only fills to approx 2/3 to 3/4 of what it would with no throttle. This will bring the effective compression ratio down to approx 10ish, 11ish or 12ish   to 1 compression ratio.
  Just a wild estimate but ignition advance should be approx 12 to 18 degrees at 1800rpm. 
  The sites that cater to mini tractor pullers running modified 16HP Kohler 341 engine series. They are one stop shopping to add solid state ignitions to any single and twins.



Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on March 25, 2015, 03:34:58 AM
B&D-  Earlier in the thread compression and octane was covered- the Lister CS design is VERY easy to lower compression on, and I have . I'm not having pre-ignition problems at all after adjusting the spark timing by ear.  I'll be fine tuning the compression for maximum load later.

I installed the new two stage regulator Thob recommended, and had to cut it's spring to get the pressure down to 11 inches of water pressure. 

The engine starts missing  immediately at 11", won't start and run at all at 8", is happier at 15+ (off scale for my gauge).  While cranking, the pressure gauge shows swings down to 3.5" on each intake gulp. At speed it's a blur with movement, though not moving as much.   I'm going to  experiment a bit to see how much is regulator, 3/8 supply hose, etc., by moving the pressure gauge to just after the regulator instead of right at the carburetor inlet.   Perhaps a buffer tank before the carb is needed per 38ac's comment and/or a bigger diameter hose.

I'm looking forward to trying Gary's CA110, since IMPCO noted it as good for single cylinder gulpers, and there's the possibility that I've got a bum CA55 carb.   

I've got a vacuum gauge I'll rig up on the intake manifold, per Gary's good suggestion.



Title: Re: DES 8/1 Propane Conversion project
Post by: dieselgman on March 25, 2015, 03:46:48 AM
Regulator to carb hose size we use is 3/4" and although I have not done much about instrumenting, I think we are running very low pressures... certainly nothing near 11" to 15". If my memory serves, it is a lot closer to 5" (but I am likely confusing pounds psi with inches of water column). Of course much of this design is based on the Natural Gas equipment used for the Lister HRG twins and triples. The fuel flow in these is designed around high volumes and low pressures.

dieselgman
Title: Re: DES 8/1 Propane Conversion project
Post by: 38ac on March 25, 2015, 12:49:16 PM
As to what Gary said about volume at low pressures this is the fuel set up on my Eclipse well engine. It is 4HP and in the same ballpark as to bore/stroke as the Lister. The fuel pipe going to the  demand regulator is 1/2" pipe. The feed pressure is about 16" it could be much lower if not for the same feed also going to the hot tube burner. The engine feed pressure is cut back considerably by the demand regulator. I cant say exactly how much because there is no place for a gauge. It has to be very low because the propane is fed through a ring of holes in the intake valve seat. I guess it isnt over  couple ounces or it would lift the atmospheric intake valve off it's  seat. This engine originally ran on well head gas but since the demand regulator is adjustable switching to propane was as easy as finding the correct pressure output from the regulator and changing the jet in the hot tube burner. Not sure what of this helps but it illustrates the need for the fuel pipes to have size when they are handling very low pressures.
(http://oi48.tinypic.com/2qwhkb5.jpg)
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on March 25, 2015, 04:22:28 PM
Thanks, Gary and Butch. I'm thinking of separating the two stage regulator, putting the small low side regulator right at the carb.
 
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on March 26, 2015, 09:04:42 PM
I split the two stage regulator and put the low pressure half on the carb/pressure gauge inlet.  Much less pulsing, about -3.5 inches while cranking.  If I increase the pressure to 15 inches it will start and run continuously if adjusted full lean (edit), though missing significantly.  I wish I hadn't cut the spring on the regulator, as about 15" of water pressure is now the max I can get, and this carb seems to need more.

I think I have a carb problem at this point.  I'm hoping Gary's CA110 will be a game changer.

Bruce

(https://farm8.staticflickr.com/7621/16731504627_4945cce8f9_o.jpg)
Title: Re: DES 8/1 Propane Conversion project
Post by: Tom on March 26, 2015, 10:39:01 PM
From the looks of the neighborhood it's a good thing you're not trying wood gas. Try a shim under the spring for more pressure.
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on March 27, 2015, 04:08:50 AM
Got some help later today and got in some long engine runs with the newly modified 2 stage regulator. Boosting the first stage regulator output to 15psi was helpful. After several runs and some fiddling, I've figured out that it starts well cold and runs well for a short while because it's TOO RICH.  I misread the carb adjustment indicator letters (oops, wrong glasses) and it's full lean that it likes.

Turning down the pressure to 6" helped a lot once it warmed up and started missing, but as it gets fully warmed up it still misses.  I tried pinching off the hose to the low pressure regulator, down to about 2-3" of water pressure at the carb.  That seemed slightly helpful but does not solve the problem.  It may be too low for the carb to regulate the fuel mixture properly.

I'm very frustrated with the CA55 carb- there is not enough range of adjustment of the fuel mixture.  The split two stage regulator was a big help, got it running well enough, long enough, to start figuring things out.  Thanks, 38AC for sharing your photo of your setup.  It got me thinking about two stage regulation and a regulator right at the carb, which really helped.




Title: Re: DES 8/1 Propane Conversion project
Post by: dieselgman on March 27, 2015, 04:35:50 AM
I think you are on the right track with leaning the mixture out, even though some of the symptoms appear logically the opposite. It will be interesting to see what the larger carburetors will do on this small engine. They have considerably larger diaphragms than the 55 and should be responsive with very low fuel pressures.

dieselgman
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on March 27, 2015, 05:54:04 AM
I'm thinking about making more of an air bleed on the CA55 carb to lean the mixture.  There's a port that seems to be for priming that I can open, plus another screw that seems to be an air bleed as well.   I can't seem to reduce the fuel enough so perhaps more air will help. 


Title: Re: DES 8/1 Propane Conversion project
Post by: buickanddeere on March 27, 2015, 10:11:04 PM
15", not 15 psi I hope ?
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on March 28, 2015, 03:16:16 AM
15 psi into a propane carb would certainly be interesting to watch, on someone else's engine and carb.   


Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on April 01, 2015, 06:49:08 AM
Still struggling with the lack of application data from IMPCO and their dealers.  One dealer thought my problem was not the CA55 but the regulator, and that I should be using an IMPCO model J regulator.  I found that the model J has -1.5" WC pressure output. Tonight I finally found a reference for the CA55-598-2 model on a retailer's web information. It seems the CA55 carburetor takes -1.5 " WC pressure.  A long way from the +3 to 15" I've been feeding it!  This would account for the rich fuel mixture.   I'm now in search of a low pressure regulator with -1.5" outlet, and 15 psi inlet. 

I got the CA110 and CA125 loaners from Gary a few days ago.  They are both single diaphram models that may handle one cylinder, slow engines better.  Thanks, Gary (dieselgman, DES), I'm very grateful for your generosity and support! 





 
Title: Re: DES 8/1 Propane Conversion project
Post by: dieselgman on April 01, 2015, 10:48:33 AM
I see that the J type Impco regulator is commonly used on forklift engines... we have a couple of them in service at our shops.  There are plenty of forklift servicing agencies and lots of parts around for them, so it should not be that hard to scare one up for your project.

dieselgman
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on April 01, 2015, 04:05:45 PM
Yes, the Impco model J and clones are readily availble and cheap.  The Cobra model regulator is it's less troublesome upgrade.   They need at least 30 psi input, up to 300 psi, they are designed to connect direct direct to the propane tank.  I've not been able to find something for 10-15 psi input, the more commonly used propane intermediate pressure.

For low pressure models, the Garretson KN types take 13" or less in, and have -0.5" out.  Ditto for the Beam 202ANL.

Centuryfuelproducts.com carries quite a selection at very competitive prices.

Update: looks like the Garretson KN type is the way to go after talking with my propane supplier, as distribution above 10 psi is not encouraged, and the tank is 50 feet from the engine shed.  So we'll use the standard 10 psi distribution in the yellow propane Pex-type pipe (buried) and down regulate to 11" at the generator shed wall, then at least 1/2" hose for the sort run to the KN type regulator.

The Model 100 may be the best carb for the Lister CS:

"The Model 110 carburetor/mixer is designed primarily for one and two cylinder engines where severe
intake manifold pressure pulsations are present. However, its use is not limited to these applications. Improved
mixture control and air-gas valve durability can also benefit other applications in intake systems where
pressure pulsations could adversely affect a standard 100/125 model assembly."
 
SPECIFICATIONS
Fuel Type .......................................... LPG Vapor
or Natural Gas
Inlet Pressure .................................... -1.5”w.c. (-0.37 kPa)"

So either way (CA55 or CA110) I need to get my pressure way down.





Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on April 01, 2015, 05:16:21 PM
I highly recommend centuryfuelproducts.com.  They actually have helpful technical support.  They suggested the IMP52 regulator, which takes 4-12" WC in and has the -1.5" output that the CA55 or CA110 need.  $59.   Shipping to me today.  Their technical guy thought I should start first with the CA55 carburetor.
Title: Re: DES 8/1 Propane Conversion project
Post by: 32 coupe on April 01, 2015, 11:18:39 PM
I would like to add that this experiment has kept me "on the edge of my seat" !!
Anxious to see.the final result.

Gary


Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on April 02, 2015, 02:50:15 AM
There will be more issues to work out but that's just the way it goes when you're doing something new.

I had to flatten the head and cylinder the other day; I was waiting on that until it went to the machine shop for the hardened valve seats.  It developed a fire ring leak into IP side 6th bolt.  Head was concave, cylinder top also, so not enough pressure in the fire ring on one side, only 1/4 from bolt hole.  Took a few hours even with help on 100 grit sandpaper on glass by the farmer method. 

I suppose the Rajkot Listeroid mod to eliminate the ring-side bolts and raise the liner protrusion where attempts to solve this QC/tolerance problem.  Alas, the latter just created new problems. 

Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on April 10, 2015, 04:25:28 PM
I got the new -1.5" water column regulator plumbed up and did another test run yesterday.  Alas, no change, still missing; carb rich/lean adjustment seems to have little effect now.  I lowered the compression ratio to 13.3 before this run, which increases the problem as it did before, when I raised it to 13.9.  I also replaced the breadboard spark circuit with a soldered board. 

The engine will not start or run cold on spark, only on the smartplug. Once it warms up a little, it runs on spark with less missing but still intermittent missing, then running, then missing, worse as it reaches full temperature.  Adjustments to the carb main rich-lean mix, idle bleed screw and hand choking have no effect. 

Today I'll be removing the CA55 and disassembling for inspection, and mounting the new adapter plate for the CA110 and CA125 carbs to the intake via JB weld. 

Title: Re: DES 8/1 Propane Conversion project
Post by: Tom on April 10, 2015, 10:34:59 PM
Bruce, Perhaps if you put an induction timeing light on the spark plug wire you'll be able to see if the plug does not fire when it misses. It could be that there is just not enough umph (technical term) to make a spark at speed.
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on April 11, 2015, 12:42:00 AM
Good theory, Tom.  I don't think the spark is intermittent, since the smartplug has the same trouble,  but I'm wondering if the spark is adequate to get ignition.  From what I've read, propane demands a high power spark system, even more so for a lean mix.  I also wonder about sparking in the indirect ignition chamber...where it could be even leaner.  I know the woodgas guys got it to go but woodgas is very different than propane. 

I might try the CDI ignition hardware I have.

I've got the CA110 mounting plate secured to the intake manifold, fiddling with the plumbing now. 

I did take apart the CA55; there is no rubber diaphram, instead, the diaphram is a roughly 2" diameter plastic and aluminum piece with a single plastic ring that rides in a cylinder.  It has a metal projection that is the main metering element, and a big 2 diameter spring pushes it closed, acted against by the intake vacuum. The internals were clean, new, unworn, smooth.  I saw nothing that led me to believe it was damaged or defective.

I hope to have the CA110 going this weekend.  It's so huge, an intake restriction will surely be needed!





Title: Re: DES 8/1 Propane Conversion project
Post by: Tom on April 11, 2015, 12:52:07 AM
My thought is that there just might not be enough voltage to jump the gap at the high compression ratio with propane. It would only take 5 min to setup and test, although I don't really claim to understand the smart plug.

I had a '71 Triumph Spitfire once with a GT6 engine swapped in. The thing ran great cold, but once warmed up it would start to miss around 4k rpm's. What I eventually found was that the GT6 engine came with an internal resistance coil and the Spitfire had a resistor on the firewall. Running both left the ignition system with just not enough voltage to work at high RPM's. Removed the balast resistor on the firewall and joy of joy's the thing ran great!
Title: Re: DES 8/1 Propane Conversion project
Post by: dieselgman on April 11, 2015, 01:10:14 AM
Bruce, 

Even on the HRG twins and triples, an intake restrictor is used. I would have to go measure one to be completely accurate, but I believe it closes the inlet down to about 1" diameter.

dieselgman
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on April 11, 2015, 03:50:15 AM
Tom, after thinking about your good suggestion some more I ordered a couple types of spark testers, just in case.  One will let me test the spark strength, the other let's me see if it's sparking when it's missing.  I'm looking at high output coils as well, but the CA110 will give me some good data before I order one.  I am using resistance ignition wire, the carbon fiber type. 

The CA110 has a big diaphram, some sort of paper or fabric type stuff, coated with brown goo (some sort of oil). Much more diaphram area, a bit less mass to move.  Many thanks for the loaner, Gary! (dieselgman).  I've just got to cut a gasket, and bolt it on my new adapter plate which is JB welded  to the intake manifold.  I'll plan on less than an inch of inlet opening...thanks!



Title: Re: DES 8/1 Propane Conversion project
Post by: dieselgman on April 11, 2015, 01:20:42 PM
Bruce,

That is a used 110 carb and apparently had been run on a dirty fuel supply at some point. The diaphragm should be clean and is normally a slightly glossy flexible material. We have repair kits for them that include the diaphragms.

dieselgman
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on April 12, 2015, 11:03:05 PM
Good news-  the engine starts and runs pretty well on the CA110 carburetor!

It struggles a bit at no load- carb gets closed down all the way and it then misses a beat but continues in a stable manner and at the set rpm.    I have to fiddle with the idle screw still, and also with the governor for load/no load.  I hooked up the compressor for a load and pumped up a tank to 150 psi.  No problems at all. The main mixture doesn't seem to affect running at idle or at load.  No signs of knocking at 13.25 compression, I'll consider raising it after a max load test.

The one adjustment that is critical is the intake restriction.  I used a PVC ball valve that was a close friction fit into the intake.  Too much restriction and it starts to miss, too little and it also starts to miss.  It likes about one square inch of opening area.

No EGT yet, which needs to be done, as well as fine tuning spark timing. etc.

Many thanks, dieselgman for the CA110 loaner!!!

Video perhaps tomorrow when I can get some extra hands.

Bruce



Title: Re: DES 8/1 Propane Conversion project
Post by: 32 coupe on April 13, 2015, 12:30:49 AM
Good deal Bruce !!!!
It looks like you are making progress now !

Gary

Title: Re: DES 8/1 Propane Conversion project
Post by: Tom on April 13, 2015, 01:52:32 AM
Your making progress and power, awesome!
Title: Re: DES 8/1 Propane Conversion project
Post by: dieselgman on April 13, 2015, 01:56:43 AM
Glad to hear that you are making progress... fine tuning will probably take care of your remaining symptoms.

Here is the inlet restrictor as used with the HRG... 2 1/2" inlet reduced to 1 3/8"

(http://mbryner.fatcow.com/listerenginegallery/main.php/main.php?g2_view=core.DownloadItem&g2_itemId=13837&g2_serialNumber=1)

dieselgman
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on April 13, 2015, 03:55:36 AM
I worked the rest of the day on adjustments- solved the no load issue with the idle bleed screw.   Running the 2 stage compressor for a load, I then gradually increased ignition timing to increase power.  I have some "head room" via throttle now with the compressor pumping into a 150psi tank.  Before advancing the timing, it was maxed out at 150psi.

I'm not hearing any signs of pinging (precombustion) under load so far, so it seems I can probably increase the compression ratio back up to 14:1.

The governor spring was replaced with the famous Home Depot spring and it worked good enough for where I'm at right now, about 40 rpm from no load to "full" load (air compressor).

I was then going to try some loads on the ST-3 but was stymied by it not working.  First there was gunk under the brushes so no contact, then no joy despite flashing.  It has an AVR that was hooked up by CGG to bypass the harmonic winding, and I'll have to check that out tomorrow.  The bearings are moaning already, on a new unit.  Grrr.

It seems Gary's CA110 has saved the day!





Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on April 13, 2015, 08:46:29 PM
Got my timing checked via strobe, and I'm still way to retarded.  Seems there is more lag to the hall effect switch than I anticipated.

The dilema is that the IP cam lobe on this engine is so seriously retarded (17 degrees ATDC) that I can't advance the timing any more without fixing that problem. 

I'm going to pull the camshaft,  move the IP lobe, and have it welded.   Anyone know what the spec'd angle is? 





Title: Re: DES 8/1 Propane Conversion project
Post by: Thob on April 13, 2015, 10:37:08 PM
Got my timing checked via strobe, and I'm still way to retarded.  
...

Don't feel too bad.  Sometimes I'm way too retarded too.

Is it possible to move the magnet to the flywheel instead of where the IP was?  I think a lot of engines run this way - it gives you an extra spark on the exhaust stroke, which doesn't harm anything (unless the spark is way retarded and happens on the intake stroke).  You can vary the timing by moving the sensor around relative to the flywheel.

I was thinking a little about your injection pump cam and wondering "how could it be that far off?".  Then I realized that the IP doesn't inject at the peak of the lobe - it injects somewhere on the upstroke, before the peak.  It pulls in more fuel on the downstroke.  So maybe it's in the right spot?

Sounds like you're getting close!
Title: Re: DES 8/1 Propane Conversion project
Post by: Tom on April 13, 2015, 11:28:03 PM
I'm still way to retarded.

I've got that problem too. Glad to hear about the progress. Can't wait to hear a video of it running sweet under load.
Title: Re: DES 8/1 Propane Conversion project
Post by: dieselgman on April 14, 2015, 03:24:54 AM
Lister published a specification that says "fuel starts" at 18 to 20 degrees btdc. Actual lobe position may be considerably off this mark because fuel starts sometime during the ramp lifting the pump tappet.

dieselgman
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on April 14, 2015, 04:10:27 AM
Gary, thanks, I did look up the specs.   I guessed at about 14 degrees BTDC for the cam, which puts IP firing 5 degrees before the lobe tip.  I'll find out tomorrow how it turns out.

Tom, yes, I run a bit retarded most days, myself. Noticeable lack of pep...   ;)

Thob, yes, there's always the wasted spark method via magnet on the flywheel (at twice the power consumption), but I've grown attached to using the IP cam follower.

 I pulled the camshaft and moved the IP cam lobe to where I think should be for diesel operation.  I needed to pull the flywheel to fix an oil pump plumbing leak anyway, and I wanted to raise the compression ratio back closer to 14:1.  So it all came apart, again.  

I was going to use 38ac's set screw method for testing purposes, but I could not get even a cobalt bit to drill through the cam lobe collar; it was that hard!  By that time I was pretty tired so out came the JB weld.  I think that should be adequate without welding since I have no IP.

Tomorrow I'll get it all back together and see how I did on the cam lobe timing.  Then I'll find out if I must add circuitry for retarded starting timing when I get the running timing properly advanced.  
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on April 17, 2015, 03:07:34 PM
I've been delayed by other parts of Jeff's new homestead project but wanted to update this thread.

In checking out my modified IP cam lobe placement, which came out well, I found a big oops.  The exhaust valve cam lobe has a big problem.  It was not really closed when I set my lash by 38ac's method, it was actually .003" open, on a flat part of the cam.  So it was cracked open during the intake stroke, and for about 20 degrees.   If I open the lash to avoid the long flat ramp , then the exhaust closed event is way off.  Either way the exhaust open event is way off.

This may account for some of the odd temperature related behavior on the CA55 carburetor, where it would start and run fine, the start missing as it started to warm up.  

I'm annoyed with myself for not fully mapping out ALL the cam lobes, and that's next.  
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on April 18, 2015, 07:53:09 PM
The big oops is entirely my own goof-  when I reinstalled the camshaft I got it off one tooth. 
With lash adjusted for center of spec exhaust closed, and intake closed, my errors are reasonable;

exhaust open: 56 degrees BBDC (1 degree out of spec)
intake closed:   5 degrees ABDC (10 degrees out of spec)

The relocated IP lobe  (formerly 17 degrees ATDC) is now centered on 4 degrees ATDC.  This solves my timing advance problem.

Now for some start/load testing with spark BEFORE TDC!


Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on April 22, 2015, 03:20:49 PM
Back to load/ignition timing tests yesterday afternoon.  At CR=14:1  I have LESS power (opening carb has little effect when at full compressor load) than I did at CR= 13.25.  Knocking is pronounced unless spark retarded to an inch (flywheel)  ATDC.

 When last running at CR=13.25, the engine spark was 4 inches ATDC (retarded) as that was the limit of advance until I moved the IP cam lobe. With the full compressor load (pumping at 150 psi near 780 rpm) I still had advancing throttle response.

I plan it to fiddle some more at 14:1, perhaps get the ST-3 going for a known wattage load test, then reduce CR to about 13.5.





Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on April 23, 2015, 12:22:07 PM
I'm getting the best power at a bump clearance of 0.098", and spark timing near TDC at my 5600 feet elevation at about 70F.  Advancing timing further does not add power under full load, only raises the no load speed.  Increasing compression to 14:1 did not increase power.  I'm a bit short on power, though the engine is not broken in.  My operating rpm is  800 at 60 Hz on the generator head.  It will sustain 2000 watts, not much more.  850 rpm is the rated speed for the 8/1.  I'm not sure how much I could cheat that upwards and the next B pulley size larger for the generator head will exceed that.  Any thoughts on a safe max speed for the DES 8/1 on propane?

I did move my magnet to the flywheel with a wasted spark.  It gives me more stable timing, the IP cam method varied 3/4  inch or so on the flywheel as the hall effect sensor I'm using is not the stabilized linear variety.

I should have some help today to do more load and fuel mixture adjustments.  And hopefully a video.

I may hook up a CA125 that Gary loaned us today.  Starting and running on the CA110 has been problem free since I opened the idle bleed screw for improved no load running.  The main fuel adjustment seems to have little effect. No EGT testing, yet.



Title: Re: DES 8/1 Propane Conversion project
Post by: dieselgman on April 23, 2015, 10:18:28 PM
The 8/1 is designed for 850rpm... some of the makers pushed them up as high as 1,000. I do NOT recommend running that higher speed. 850 is fine, maybe 900 would not be pushing it too far.

I cannot really say what additional stresses might be encountered with the propane fuel but it should all be fine unless you are experiencing any pre-ignition knocking or pinging.

dieselgman
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on April 24, 2015, 02:01:33 PM
Thanks, Gary.  I'll keep the speed below 900.   I think we are very close to meeting our power goal at 810 rpm/60Hz , so perhaps no pulley change will be needed.

Had some help yesterday and found better power at further reduced compression.  Bump clearance now at 0.122", spark timing at 1/2" ATDC.  I was able to run the air compressor at 160 psi and add another 500 watts on the ST-3 (no throttle left).  With the compressor unloaded (but belted as a parasitic load) at 2000 watts of load on the ST-3 there was still throttle response.  There is still a bit of knock when opening the throttle at full load, so we may try another reduction in compression, and I still need to try spark timing adjustment at the newly reduced compression.

I also need to try running my 1/2 hp submersible well pump, then starting the washing machine, with the compressor belted but unloaded.  That's our max load for Jeff's system, also.

The ST-3 on a single B belt driven flat on the flywheel seems to work fine.  The single B belt for the air compressor is OK so far but did have to be adjusted for some stretching so I'll keep an eye on it.  I went with single B's to keep a possible rpm change affordable.

CA125 carb testing soon, EGT measurement also.







Title: Re: DES 8/1 Propane Conversion project
Post by: buickanddeere on April 24, 2015, 07:56:49 PM
Sounds like you are the right track. Just too much mechanical compression ratio with a low rpm and a short duration cam . The cylinder pressure and heat from compression is taking the LP above it's auto ignition temp.
    Iirc about 11 to 1 is about max for LP withow rpm industrial engines.
  Is there any quench in the combustion chamber or is it open ?
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on April 29, 2015, 01:39:00 AM
B&D- the Lister CS is an indirect injection engine with otherwise little in the way of concavity in the head.

I hooked up the Impco CA-125 carb today.  It starts and runs nicely without any intake restriction.  I do have markedly less power, and more clearly noticeable knock at load, but the adjustments all work and have an effect, including the main rich-lean adjustment.
I may fiddle more with it once the compression is lowered, again.






Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on May 08, 2015, 05:41:16 AM
Waiting on the machine shop for the hardened valve seats... meanwhile my new neighbor is camping in a small storage building and the generator/DC power shed until the shop building interior is completed, then I can set up the engine in it's permanent home.
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on May 30, 2015, 04:19:09 PM
Got the head back from the machine shop who installed hardened valve seats for propane use.  We also had the head and cylinder planed.  Alas, though I didn't see it before, now you can clearly see a hairline crack near the web between COV and coolant passage.  It is not in a thin section, seems to be a casting (shrinkage) flaw.  It took some side lighting and fiddling to get it to show up in the photo.
 
(http://i1119.photobucket.com/albums/k626/rbmccreary/DSCN0242-001_zpsld1rpt3o.jpg) (http://s1119.photobucket.com/user/rbmccreary/media/DSCN0242-001_zpsld1rpt3o.jpg.html)

I lack the expertise to know what to do about this.  Should we get a replacement or just run it and see if we get bubbles in the coolant or around the COV plug?  


Title: Re: DES 8/1 Propane Conversion project
Post by: 32 coupe on May 30, 2015, 05:28:28 PM
OUCH ! The crack may not go all the way through. It may just be a casting flaw.

I would give it a try before I gave up on it.
It would take some work to pressure check it. A custom head plate or assmble engine
then pressure check.

Gary


Title: Re: DES 8/1 Propane Conversion project
Post by: dieselgman on May 30, 2015, 08:18:10 PM
I concur with testing rather than assuming that is indeed presenting a problem (especially after investing the machine work in that one). There are quite a number of fine scratches in that surface but it is impossible to tell from the photo exactly what is a surface mark and what might show an actual casting flaw.

We will replace it later, if it proves to be a defect.

dieselgman
Title: Re: DES 8/1 Propane Conversion project
Post by: 32 coupe on June 07, 2015, 02:54:35 PM
Hey Bruce,
Have you had any luck yet ??
Gary

Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on December 19, 2015, 02:12:10 AM
There's been a long hiatus on this project, due to the generator shed being used for temporary living space while the shop building was being completed for heated winter quarters. We are now back to the fine tuning, with the engine now housed in the permanent generator shed and supplied via the home propane tank and exhausting into an leach field type "earth muffler".  We made a copy of my pneumatic exhaust valve lifter and have electronic push and toggle button control of all the necessary functions now. Remote starting will come next.

The engine was starting flawlessly and running well but either cold weather or the planing of the head and cylinder by the machine shop raised the compression too much and we had a pronounced knocking at load (air compressor).  We tore her down and added 0.075" under the cylinder. That improved the knock and power significantly but was still slightly present at load.  We added another 0.030 and suddenly it would not start, and we're smelling a lot a raw propane. We would get maybe one ignition, then nothing.   Spark was confirmed good visually and by timing light when cranking. Compression is fabulous, no leaking. The CA110 carb diaphram was checked and still looks fine.  Very odd to suddenly have a no start situation with lots of raw propane smell after such utterly reliable and unfussy starting.  I next checked the IMP52 regulator, and we seem to be getting gas leakage on it's output, which should require negative pressure, so I will call Century Fuel Products Monday and hope to get some advice.

Very frustrating to be so close to getting her finally "dialed in" and then to be back to a no start situation.

Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on January 02, 2016, 07:36:40 PM
We've got her starting and running quite nicely again. Our problems were my homebrew spark module, confirmed via spark timing light.  It still misses under heavy load after a bit of run time and also with the generator head, but this has been confirmed as glitches in my 555 based hall effect/dwell circuit, with secondary failure of the power transistor due to coil kick back.  Coil voltages climb as compression increases with load.

I am hoping some auto savy readers might be able to suggest a three or four wire COP (coil on plug) unit that I could readily use.  Ideally it would be a unit that has a short spark plug wire, not a direct to plug type.  I have seen photos of such things but can't seem to find a make and year so I can purchase one.  My spark plug is buried in the head with access too narrow for the direct to plug type.  I need make, model and year(s) for your suggestion.

 I think Jeff would be best off with a single commercial COP unit that replaces coil and ignition module in one for ease of swap out troubleshooting/maintenance.  Then only my hall effect/dwell timing circuit is custom, and it has a blinking LED to confirm it's operation.

 My plan B is to go to a 4 wire GM HEI ignition module and our existing coil, that will be time consuming as it's designed for a reluctor/coil type input and what I have is hall effect, so I have to fiddle with a conversion circuit.

Title: Re: DES 8/1 Propane Conversion project
Post by: EdDee on January 02, 2016, 09:58:24 PM
Hi Bruce,

What about a SCR in lieu of the transistor? Swing the gate to negative trigger voltage to break the latch...

Regds
Ed
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on January 02, 2016, 10:23:10 PM
Thanks Ed. There are plenty of cheap high voltage igbt transistors; due to the low spark rate, this one doesn't work very hard and stays cool.   I just didn't realize the flyback voltage would go to 500v+ on an HEI spark test plug.  I will add a better snubber to lower that a bit.

A 3 or 4 wire ''Coil-Near-Plug'' ignition coil sure would be nice; coil and ignition module all in one.  I just need to find a popular one so it's affordable.

Meanwhile I'm separating the dwell timing from the ignition switching, and sending the timing pulse via plastic optical fiber, since I have plenty of those relatively cheap parts on hand.  I've got a 600v IGBT transistor on hand I can use for switching, and will mount it on perf board spaning  the coil terminals.  Hopefully that will let us go forward while considering other options for long term.



Title: Re: DES 8/1 Propane Conversion project
Post by: EdDee on January 02, 2016, 10:28:56 PM
Agreed Mike...

What about really old school.... mech point and condenser...simple, easy, bullet proof? ... don't need advance/retard either because of fixed speed.... or on the other hand, the Honda Gx340 has a built in ignition circuit in the magneto coil... or like the robin EC10, a single wire module instead of the points, fitted as an aftermarket replacement often...

Regds
Ed
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on January 03, 2016, 03:35:20 AM
A wasted spark system with mechanical contacts would be doable, though a pain the implement mechanically. I'd rather go with a modern electronic spark system.  I already have a dual hall effect spark timing system that works well and was very easy to implement.  One hall sensor is sensing the IP cam follower (with magnet on top) , which enables a second which senses a magnet on the flywheel.  Under $2 including the ceramic magnets.

Both the honda gx340 and the robin ec10 seem to be quasi-magneto spark systems,  I'm much more interested in an automotive coil-near-plug with ignition module integrated into the coil.  If only I can find one, preferably one in high volume with aftermarket parts available.

If someone knows of a vehicle with a coil-near-plug (3 or 4 wire, integrated ignition module) I'd sure love to know the make, model and year(s).
 



Title: Re: DES 8/1 Propane Conversion project
Post by: buickanddeere on January 04, 2016, 03:16:55 PM
Just use the platoon sensor and transistor pack from a 80's vintage Dodge .
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on January 04, 2016, 05:57:48 PM
B&D - Thanks, could you maybe suggest a specific model and year?  What the heck is a platoon sensor?  Ford used hall effect, GM used reluctor type inductive pickups, but I've never heard of a platoon. 

I revised my spark board to optically isolate the spark driver from the hall effect/dwell timing section, and added 9v linear regulation to the hall/dwell section to give it better noise immunity.  That and adding 0.2 uF of capacitive snubber across the coil seems to have done the trick.

I still have some knocking at full load and temperature- so more shimming of the cylinder is needed today.  I did my full load test yesterday- compressor unloaded, 1/2hp submersible well pump running 1140 watts, washing machine starting spin cycle.  It handed it OK. 

Some serious carb metering issues still with the CA110 propane carb.  I have to manually adjust the fuel mixture via inlet restrictor for each load.  It needs to be richer to start and no load, leaner proportional to load.  There is supposed to be a way to shim the fuel mixer to adjust this- but I haven't been able to find a ''how to'' article yet.   The fuel rich/lean adjustment on the carb has no effect at all.  The idle air bleed adjustment has only a minor effect.  I get missing (no combustion) and/or backfires (more like a little pop) when the fuel mixture is off.  Spark is confirmed during missing via inductive pickup timing light. 

I think we'll try the CA125 carb again and see if that behaves better.   

I'm going to look for a VERY long reach plug in hopes of changing spark placement within the pre-combustion chamber, and also will try increasing the spark gap in hopes of lessening sensitivity to fuel mixture.  I have already bench tested the spark system with a huge gap and the flyback voltage was still OK with the new 0.2 uF snubber.

Title: Re: DES 8/1 Propane Conversion project
Post by: Tom on January 04, 2016, 07:18:23 PM
A 2001 Subaru has a very long reach plug. The 2500cc 4 banger.
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on January 04, 2016, 08:08:59 PM
What model Suburu, please, Tom?

After reading the Impco training manual I'm getting suspicious that the CA110 carb might be having trouble. It seems I'm going to learn a lot more about propane metering/carbs than I'd like to.   ;)   Shims under the metering valve can be used to lean the full power mixture, and that may be something I need to do. 

One concern I have is the abrupt lack of ignition we get when the fuel mixture is too rich or lean. That's not normal.  Sparking in the indirect injection chamber is less than ideal.  I'll proceed and hope I eventually get it figured out or, preferably, just get the lucky combination that works.  One thought I had is to have the cylinder head plug bored and tapped for the sparkplug, and then I could make a hollow cylinder that would fit in the injector hole.  This would help reduce compression (and our growing stack of shims) and allow more fuel mix to flow into/through  the combustion chamber.  Just rambling, I hope that isn't necessary.

I'm adding a neon spark indicator to the coil- powered by the flyback spike.  It should let me reduce the snubber capacitor (condenser in automotive speak), and having a visual spark indication is handy when trouble shooting rough or missing situations. It will let me have less wiring dangling around, as I've been using the timing light for this.





Title: Re: DES 8/1 Propane Conversion project
Post by: mike90045 on January 04, 2016, 08:17:37 PM
air fuel mixture under compression, requires a higher voltage to fire the plug.
Title: Re: DES 8/1 Propane Conversion project
Post by: Tom on January 04, 2016, 08:22:44 PM
Outback, but all the engines are the same. Does this look like what you want?

(https://www.rockauto.com/info/341/41-602_Primary__ra_p.jpg)
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on January 05, 2016, 12:55:20 AM
Thanks, Tom.  That's the standard "long" spark plug. 

Good point, Mike.   We did some more experimenting today and found the spark system is still not 100%. It ran more reliably with smaller spark gap- which reduces the voltage required.  We did see some missing on the timing light at larger gap when it did occasionally miss.  So we have two problems still - spark and carb, which makes me appreciate diesels. :)

I'm ready to switch to a Dephi GN10119 or UF262T integrated coil near plug unit.  They are GM 4 wire connector units that take a positive (5V) dwell pulse, fire on falling edge.  I was able to find the pinout info.  They are used in Chevy Avalanche 1500  trucks from 2002-2005 and Silverado 1500HD from 2001-2007.  PITA to find connectors for them.  We'll  make a mounting bracket to fit the injector hold down bolts.

I'll make my dwell circuit adjustable so I can adjust the spark intensity easily.  We're also going to make a new bracket so the flywheel hall effect sensor can be moved while the engine is running to make fine timing changes easier.  We've got a few days of bad weather to work on this sort of stuff.

Jeff and Mark put on the CA125 carb this AM and tried it, again. Starts runs lovely with no inlet restrictor at all but absolutely no power.  It can barely get to full speed with no load.   It just can't deliver enough fuel/air mix for the DES 8/1 at 820 rpm.  So it seems the CA110 is our best bet if only we can get the fuel metering to what we need (leaner at more throttle).

Back on the CA110 this afternoon, we tried adding a hand cut gasket as a shim under the gas valve on the CA110 to lean the full load mix- alas, it then wouldn't start.  So we will try again with thinner gasket material.  We still have to reduce compression further, now at about .420 of shim under the cylinder.  We've had to unscrew the cylinder bolts a couple turns from the block (lots of thread length in the block), and will now have to grind the rocker arms to allow extending of the valve adjust screws another 1/8".   She is getting taller!

When she is running right, she is very sweet sounding, very quiet, no vibration.  The power at 815 rpm on propane is as good or better than my 6/1 at 650 rpm on diesel.  We just need to solve the spark and carb issues and I think Jeff will have a wonderful off grid setup for his disability needs. 

The earth muffler (septic leachfield for exhaust) works fabulously well.  We put it in when the septic guy was installing the real leachfield, so it was relatively cheap and easy.  There is NO exhaust sound, and the air coming out of the vent at the end of the muffler smells only like damp earth.  There is so much cooling of the exhaust gasses, that there is almost nothing coming out at all.

I'll try to do some videos with sound sometime soon.

Title: Re: DES 8/1 Propane Conversion project
Post by: 32 coupe on January 05, 2016, 04:24:19 AM
Bruce,

I'm not.sure if I understand your exhaust system .......???
Could it be that the exhaust system is restricting the engine and
thus the fuel mixture problems ?

Gary

Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on January 05, 2016, 06:14:46 AM
We also have a port outside the generator shed where we can screw in the stock "pepper pot" muffler;  I used that initially so I could see the exhaust.  It's a good idea for us to confirm our rich on full load situation with the pepper pot in place just to see.  Thanks for thinking of that Gary.

Our leach field "earth muffler"  is a 24" wide, 3.5 foot deep ditch 20 foot long filled with 3" rock (1 foot of dirt on top of some aluminum flashing).  A section of about 6 feet of 2" ID pipe with holes cut on the sides and downward feeds the leech field.  A section of 4" plastic perforated drain pipe leads out of the last 6 feet and up to a vent cap above ground.  I'd be surprised if this was overly restricting the exhaust.

Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on January 07, 2016, 04:13:18 PM
Thinking in the wee hours of the AM when I couldn't sleep has me thinking about our various carb/running issues:
Both the CA55 carb and CA110 (to a lesser extent) have had an issue with missing and misfiring after the engine warms up.  The CA110 only has his issue after a longer warm up, in part because now I have a fully setup thermostat/radiator (thermosiphon driven). 

We have noticed that cold, we are getting a small amount of outgoing pulses from the intake, due to intake valve timing (intake open slightly precedes TDC).  We also notice that when having difficulty starting- we smell raw gas from the carb intake strongly.

Under full load, on the CA110, she runs fine and then after a few minutes starts missing badly, stumbling, with an occasional backfire (minor).  This has been baffling.  We have to shed load, then can only after some time slowly milk her back to running, but she will then miss with load much faster. 

I'm thinking as of this AM that what may be happening  is a cam/intake timing issue (which would NOT significantly affect diesel operation) that is aggravated by the engine warming.  The CA110 is a single diaphram type carb, which is going to be very sensitive to positive pressure pulses on the intake in terms of fuel metering.  If as the engine warms up, either intake valve timing or the intake valve seating could change, such that intake positive pressure is seen, this would totally screw up fuel metering. 

So first, after we install our new improved spark system, I'm going to carefully check both cold and hot intake open/closed timing events.  I'd love to have an analog vac/pressure sensor on the intake manifold I could watch with my digital oscilliscope!
I will attempt to shift intake timing via lash to see if we can solve this issue.





Title: Re: DES 8/1 Propane Conversion project
Post by: Tom on January 07, 2016, 07:16:31 PM
How about just putting a good old fashioned automotive vacuum gauge on the intake? They can give a lot of useful info.
Title: Re: DES 8/1 Propane Conversion project
Post by: EdDee on January 07, 2016, 10:39:44 PM
Hi Bruce,

I have another theory... I think that the slow pulsing is playing havoc with the metering diaphragm/system of the carb... possibly causing the diaphragm to 'flutter' maybe, which would give either too rich or too lean a mixture to run correctly.... in essence, you would need, I think, a vacuum accumulator of sorts on the intake manifold... Here is where it gets interesting, in my opinion, it shouldn't be an inline one, a large volume, say 3 to 5 litres of perfectly mixed gas is gonna make quite a bang if the engine backfires... so what about a t piece with an updraft carb, with the accumulator opposite the intake port? In the far end of the accumulator, have a small valve so it continually draws in fresh air to purge the tank of mixed gas. Also, add a restrictor to the mouth of the gas carb, a gate valve would work quite well, so you could adjust the vacuum in the intake system to keep it in the slightly negative pressures overall, this would be, I think, an easier way for the carb to determine when to admit gas....,

Just a thought....

Regds
Ed
Title: Re: DES 8/1 Propane Conversion project
Post by: Tom on January 07, 2016, 11:47:50 PM
Flutter is a good possibility.
Title: Re: DES 8/1 Propane Conversion project
Post by: 32 coupe on January 08, 2016, 01:48:53 AM


Check  valve lash.





Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on January 08, 2016, 03:44:19 AM
Good ideas on all fronts, guys.

Jeff and I did some experimenting today. We increased the valve lash greatly on both exhaust and intake to eliminate intake opening/exhaust closing overlap.  Intake opening is now just after TDC, and exhaust closes just before TDC.   There are still strong intake pulses, but no more outgoing puffs, which were clearly present before.  On our test run, she ran well, until the air compressor tank was almost at 135 lbs, then she started some missing and stumbling.  The missing and stumbling was confirmed as spark related via timing light. We did not have back-fires.  We had a consistent inlet restriction (almost open, 1.5" via a PVC ball valve) from very cold to hot, which is change for the better.

So we still have some spark issues to work on but I think getting rid of the intake positive pressure pulse is helping the carburetor behave much better.  I expect we will be able to reduce lash some, but we only noted about 4 lower rpm without any governor adjustment for the extra large valve lash. 

We got  the integrated coil near plug unit today and make brackets for mounting it to the cylinder head.  We have to Weldbond those in place.  Hopefully the mating 4 pin connector will show up soon. 

If weather permits, tomorrow we'll pull the cylinder again and lower compression another .075" or so, again.  We got a 3/8 aluminum plate to help reduce our growing stack of aluminum shims with paper in between. 

I like Tom's idea of putting a vac/pressure gauge on the intake.  I think Ill find a way to plumb up my Mityvac to the intake manifold; it has such a gauge.   

Ed- the CA110 is recommended by IMPCO for pulsing intake situations, so hopefully an accumulator to smooth the flow won't be required.  An accumulator causes all kinds of headaches for starting and for safety.  The idea of keeping the fuel mix out of the accumulator is good.  I'll think about it more if we just can't manage without it.




 
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on January 13, 2016, 03:48:33 PM
Some good progress to report.  The compression has now been further reduced, our cylinder spacer is now 0.510 total. Valve lash still set wide to avoid intake/exhaust overlap. We ran the GM L2 ignition/coil near plug unit yesterday with my same hall effect/555 dwell circuit and had a nice run from cold start all the way to full air tank.  Smooth running all the way, no issues.  Dwell output LED steady, steady spark as indicated via timing light. No knocking and good power. Then we strapped up the generator head and ran the well for a bit with compressor unloaded.  Again no trouble.  We then added the washing machine, starting spin cycle a few times as a load test, everything A-OK.  Big grins on our faces at this point.


Alas, after leaving the well and washer running for a while, she once again started missing and backfiring.  We then shed the load and watched the indicator LED on my hall effect/dwell board.  Sure enough, it was missing now sporadically even with no load.  So clearly we have some conducted EMI damage from the spark that is damaging the 555 or hall effect sensors.  So I have added some spike protection and will be adding some filtering on the DC power to the GM L2 unit, power in to my 555 board, and will perhaps add some protection on the hall effect sensors as well. 

I am encouraged that it appears that now most of our irregular running problems seem to clearly be spark system glitches, and that once those are fixed we should be at the fine tuning stage for the DES 8/1 propane conversion. 



Title: Re: DES 8/1 Propane Conversion project
Post by: buickanddeere on January 13, 2016, 05:08:39 PM
Thanks for the ideas, guys.
I've read about intake air restrictions being used in propane conversions on the IMPCO website-  could someone please explain why that is used?
Is this because ignition timing needs to be changed with throttle position but can't be in a typical retrofit?  I can manage that electronically if I must.

The throttled intake reduces the density of the intake charge . For instance a real effective non knocking 10 to 1 compression ratio is possible and a 16 to 1 expansion ratio power stroke. Used all the time in the econobox hybrid cars. Engines with variable cam timing do this as well at in low power cruise mode. It's also why gasoline engines advance the spark at part load.
Title: Re: DES 8/1 Propane Conversion project
Post by: Tom on January 13, 2016, 05:51:07 PM
Glad to hear you're achieving some success and are on track to resolve the final issues. I'd like to hear it run under load once you've got'er dialed in.
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on January 13, 2016, 10:13:32 PM
Thanks, Tom.  I will do video w/sound and stills for this setup once we get the bugs out.  The only sound is valve/gear train noise due to the earth muffler.  Propane and lower compression make for a quiet and clean running engine... even with the stock Pepper pot the exhaust is quite tame. We will be adding sound baffles to our engine shed air louver vents to address the valve/gear noise.  Sound was a major design issue for this project.

Today we're doing some conduit runs and adding some earth grounding via rods and copper pipe for a more permanent setup for our spark and dwell/tachometer setup.  We had just run some temporary wires for initial testing.  I'm adding a custom low pass 12 VDC power filter to the separate power run to the GM L2 ignition/spark unit, and will also filter to keep spark/ringing/spikes out of the timing/dwell and tach boards.  An analog tach is needed to make remote starting easier, as at least initially, remote control will be manually controlled instead of the microprocessor control which I have on my system.  It does call out for a PIC or Arduino/AVR controller, but I just don't have the time for that now.  My Picaxe controller is still going strong, but I didn't make PCBs for that setup; it's all very time consuming point to point wired on perfboard.





Title: Re: DES 8/1 Propane Conversion project
Post by: 32 coupe on January 13, 2016, 10:21:41 PM


Good deal Bruce !  Looks like you're geting close now.



Title: Re: DES 8/1 Propane Conversion project
Post by: buickanddeere on January 14, 2016, 03:18:30 PM
A wide band O2 sensor in the exhaust would remove all doubt about air/fuel ratios.
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on January 15, 2016, 03:27:57 AM
Thanks B&D.  Carbon monoxide measurement is what IMPCO recommends for fuel mixture adjustment of propane engines.  I'd love to have it for this project, but it's not in my budget; this is a one-off volunteer project. 

I was wiped out today from yesterday's efforts but Jeff and I did do a test run with the newly spike protected timing/dwell board.  We got a stable, no missing, output to the GM ignition/coil unit,  but spark was missing occasionally at full load & temp (inductive pickup spark timing light misses).  I increased dwell from 3 to 4 msec while it was running and the missing stopped.   We are also now running with no intake restriction at all, and have adjusted the carb for a lean mix but will have to see how that goes for cold starts.     

Storm front moving in so I may take a shop cleanup day tomorrow.







Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on January 21, 2016, 02:37:30 AM
The DES 8/1 Propane Conversion is now in service, doing real work.  We have some details to work on still, such as air cleaner and remote start, but after adding the Delphi GN10119 integrated spark/coil unit, and increasing dwell to 5 milliseconds, our problems of missing at full load and temperature are over.  The last two days it has been supporting some construction work and welding (mostly generator, some compressed air).  I took some videos late today and will upload them for your viewing pleasure.  I also have stills to shrink and upload for those with low bandwidth internet access.

I especially want to thank Gary at Diesel Electric Services for his outstanding support for this project.  His parts, knowledge and a loaner CA110 has made all the difference for power and reliability and made our project a success.

Intro video:
https://youtu.be/ol39s0ngv2U

Starting the engine:
https://youtu.be/xky2tpeHwJY

Earth Muffler:
https://youtu.be/sMu5VRA8GLM

Engine Balance
https://youtu.be/yyA9mlpyerQ


Title: Re: DES 8/1 Propane Conversion project
Post by: Tom on January 21, 2016, 05:24:01 AM
Very nice! Lots of great engineering there.
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on January 21, 2016, 07:03:13 AM
Thanks Tom.  Yep, a lot of hours on this project.  It broke my heart to not do another induced draft (via exhaust) cooling system, but I'm very happy about the earth muffler, and the thermosiphon radiator plus thermal chimney cooling system seems to be working like a champ.
Title: Re: DES 8/1 Propane Conversion project
Post by: dieselgman on January 21, 2016, 01:57:28 PM
Excellent work and good documentation! This will hopefully serve to enlighten and encourage further development along the lines of alternative fuels and truly shows what dogged determination and intelligence can accomplish!  ;)

Well done!

dieselgman
Title: Re: DES 8/1 Propane Conversion project
Post by: buickanddeere on January 21, 2016, 04:01:00 PM
Here is an article to retrofit  common off the shelf automotive electronic ignition systems onto any engine .http://gardentractorpullingtips.com/ignition.htm
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on January 21, 2016, 05:41:08 PM
Thanks dieselgman.  We couldn't have done this without your help!

B&D- great article, very comprehensive.  

Some thoughts about sparking the DES 8/1 on propane:

After some struggling due to my own inexperience with spark systems, I decided to use the venerable GM L2 system (Delphi GN10119 or UF262T), as it integrates both coil and spark module, which only leaves me with a simple 555 circuit to trigger it with a +5V dwell pulse and we have a powerful, state of the art spark system.  I was surprised that with propane, under heavy loads and full temperature, such a hot spark was needed.

Here's a nice write up on the GM L2 coil near plug units and the pinout to drive it:

http://www.megamanual.com/seq/coils.htm

We also switched to a VERY long spark plug, the NGK LFR4A-E.  It gets the tip down near the "smiley" mouth of the indirect injection cavity.  This seems to help.  

Spark timing seems non-critical,  around the normal IP injection timing or a little before works well at 810 rpm.  

Fixed timing is adequate for starting, no retarding needed.

We had to go to magnet on the flywheel for a more stable spark timing; the hall effect sensor trip point was too variable with the IP cam follower magnet alone.  So I use the IP hall effect switch set to turn on early-late to enable the flywheel sensor.  A wasted spark system does work fine, also.   I'll post a schematic for the spark/dwell circuit when I get it drawn up properly.  It is presently still in my own shorthand/hen scratch.  







Title: Re: DES 8/1 Propane Conversion project
Post by: 32 coupe on January 21, 2016, 11:19:52 PM


Good job !

It has been an interesting project. Thanks for posting.

Gary





Title: Re: DES 8/1 Propane Conversion project
Post by: Tom on January 22, 2016, 12:36:35 AM
Bruce, what would guess is the CR that engine is running now.
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on January 22, 2016, 02:18:15 AM
Hi Tom,
I haven't recalculated the CR with 0.510 of shim under the cylinder.  We just kept adding until the knock at full load went away, we had the head and cylinder off 8 times.  Every time we lowered compression, we also got more power.  It is now noticeably more powerful than my diesel 6/1.  

Edit- just reran the figures and it seems we are pretty close to CR of 10:1 now.   I suspect that the propane we're getting delivered to Jeff's tank must have a fair amount of butane and other gasses.  I was very surprised that we had to keep adding more spacers to get rid of the knock...as last summer on a different source of propane the CR was 13.5:1 with a modest knock under load.

I just wanted to also thank you, Tom, for your early "right on the mark", insightful comments on spark and higher compression requiring more energy, per your own car story.  This ended up being just the situation here, along with a host of other confounding issues.  

Gary, Thanks, and special thanks for the offset idler bolt for this engine.  

Best Wishes,
Bruce







Title: Re: DES 8/1 Propane Conversion project
Post by: veggie on January 30, 2016, 01:28:01 AM

Bruce,

Watched your vids.
Man....you did a really nice job with that propane listeroid !

WELL DONE !

Nice to see it running after all the work you have had to put in.

Cheers,
veggie
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on January 30, 2016, 03:18:08 AM
Thanks Veggie.  We're still working on details, but it does seem to be working out nicely. 
Title: Re: DES 8/1 Propane Conversion project
Post by: M61hops on January 30, 2016, 09:56:00 AM
Fantastic job on everything!  Thanks for sharing!  I'd like to convert a Changfa 175A to propane and now you've got me thinking I might have trouble getting the charge to light off consistently because I was going to replace the injector with a sparkplug at the end of a chamber in the injector hole.  It might be a bigger challenge than I was figuring between the spark and fuel mixture problems.  The 175A is just too loud as a diesel for me to use and there are no small water cooled engines that I know of in the USA.  I dream of a small CHP system for a travel trailer!   Leland
Title: Re: DES 8/1 Propane Conversion project
Post by: dieselgman on January 30, 2016, 01:19:36 PM
Leland,

Lister/Petter designed and built a number of small water-cooled as well as air-cooled diesels... mostly used in the military for aux power in the Abrams tanks, APCs, and a few other applications. Collectively referred to as the Alpha series, these units were primarily 1800rpm genset builds and apart from the Kubota super-mini are the smallest footprint and physical size in their class. DitchWitch also uses this same powerplant in their trenchers and horizontal drills. These are available in factory natural gas versions as well.

While it is a shame that Lister did not achieve EPA certifications for these, they do enjoy a very wide distribution and are coming into the used marketplace in volume via military disposals.

Take a look at the LPW2 for a cute little piece of equipment! We have them by the truckload.

We now have moved and continue to operate the L/P Americas remanufacturing operation (under new name) for these and have a massive stock of everything you would ever need to keep them going far into the future.

dieselgman
Title: Re: DES 8/1 Propane Conversion project
Post by: deeiche on February 01, 2016, 05:16:14 PM
Leland,
SNIP
Take a look at the LPW2 for a cute little piece of equipment! We have them by the truckload.
SNIP
dieselgman
Just did a search on eBay for LPW2 (http://www.ebay.com/itm/ONAN-DN2-M-LPW2-LISTER-2-CYL-DIESEL-ENGINE-18HP-MIL-SURPLUS-MEP802A-Cheap-Ship-/301843388986), price point looks good.
are yours in KS? and how is parts availability.

thx
Title: Re: DES 8/1 Propane Conversion project
Post by: dieselgman on February 02, 2016, 12:33:25 AM
We warehouse in Kansas... parts availability is excellent and in current production for these models.

dieselgman
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on March 25, 2016, 09:36:17 PM
We had an intermittent power loss and missing problem that started showing up a month ago.  Ended up being two problems- a loose connection on the spark dwell signal, and an occasionally sticky low pressure regulator.   Thumping on the regulator with a wood handle  could make it misbehave, or alternately, stop misbehaving.  We swapped in our spare and all is well again.  I disassembled the old regulator, found where it was binding, polished and oiled it.  The gulping of the CS intake is once again the issue; our IMP 52 regulator has an 1" diameter aluminum cone that is lifted by diaphram to let the fuel flow.  The shaft it moves on with was binding in it's unbushed hole in the case. 

If we continue to have problems with this style regulator, I'll suggest we try the the KN or Garretson type regulator.  Because of it's design I think it might be better for the CS intake gulping. 

I hate intermittent problems, especially when they come in pairs.  The worst of it was that the regulator problem behaved JUST like an ignition problem, so I chased my own tail there for quite a while before finally believing the evidence of the timing light and dwell signal LED indicator, and knocked on the regulator.

She is back to chugging away reliably, though we are now marginal on cooling for warmer days on long full load runs so am upsizing the cooling system.









 
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on April 10, 2016, 08:02:25 PM
Although our backup IMP52 regulator was still working fine, I was not impressed with it's internal design.  I talked with Nash Fuels and Century Fuel Products, both good Impco distributors.  They are both good outfits but have no real technical support by Impco, which is now owned by a bigger alternative fuels company.  I think they both could provide very good basic support for more typical applications.  I state this as a warning to others- there seems to be no such thing as tech support from Impco anymore, not even to their higher volume dealers.  The brilliant guys who designed IMPCO's products and knew how to apply/modify them for new applications are long gone.

I studied the Impco regulator catalog, looking closely at the internal parts in the exploded view, and found that only the Impco/Garretson KN regulator seemed suited to our gulping intake Lister clone and 10" of WP gas supply.  They fortunately are fairly cheap, on ebay for about $50, so we ordered one to try.

The KN regulator has a large 6"" silicone diaphram that operates a 2.5" long glass filled nylon teeter-totter against a spring (adjustable tension). The tetter-totter opens a silicone face disk against the about 0.5"",  10" WP brass gas inlet.  A very simple design.  We have the 3/8 NPT outlet (wish it were larger) immediately bushed up in size to feed a 3/4" hose about 24 inches long to the carburetor.  In the past with the IMP52 we've found that this hose size was required with any length over a few inches.

It started right up but lacked power initially.  With a minor adjustment to allow the internal valve to open an additional 1/16", and the carburetor adjusted richer, we seem to have a nicely working engine, again.  I'm convinced that the internal mechanisms should hold up much better to our pulsing intake than the IMP52 regulator, where an 1x1"" aluminum cone on a shaft is lifted by diaphram. The IMP52's 1/16" cone shaft was unbushed and in time it bound were it went through the die cast aluminum body.  We were also pleased that now both idle adjustment screw and carburetor rich/lean adjustments worked as they should, and with the IMP52 they made no difference at all.  This makes me pleased that we are finally "in the zone" for the CA110.

The īntake "gulping" of the DES 8/1 propane conversion seems to be THE big issue for a propane carb/regulator.  The CA110 was specifically noted as suited for this, with it's large diaphram directly lifting a metering cone (no shaft).  It seems the KN style regulator is a better match for it in this application.

I'll report back as it logs more hours of service.





Title: Re: DES 8/1 Propane Conversion project
Post by: EdDee on April 11, 2016, 09:07:55 AM
Hi Bruce,

Just a thought... All SU/Diaphragm carbs I have seen on single cyl engines and feeding a single cylinder of a multi piston engine, have a "damped" slide to take care of the intake pulsing. The more cylinders being fed, the smaller the damping system on the slide. Is there no way to put some form of damping cavity between the carb and the head, even on a T-piece? I suspect that without a fairly heavy damper on the gas metering slide, longevity might become a problem due to it opening and closing many times during the cycle as it "bounces"...

Cheers
Ed
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on April 11, 2016, 05:32:44 PM
Thanks Ed.  I did think about a reservoir approach, but to eliminate the need for regulator movement at every intake pulse would require
a volume of multiples (3-6?) the engine displacement (1.43 Liters).  That's not convenient and a safety issue.  I don't believe a smaller reservoir will eliminate gulping. It would also require a solenoid or motorized ball valve shut off lest the gas seep into the engine room when the engine is off, since the CA110 carburetor metering valve is not a gas tight seal.  The most dangerous situation would be air leaking into the the reservoir, making it a container of explosive gas/air mix.  Since this is not my engine room, and I'm just a volunteer on the project, that concerns me.

The KN regulator's moving part (besides the silicone diaphram) is very lightweight, just a glass filled nylon rocker on a steel pin pivot and by design it appears to be up to the job.  We'll know for sure in 6 months or so as the engine will be getting a lot of hours during construction of the main house, which has begun.


Title: Re: DES 8/1 Propane Conversion project
Post by: Tom on April 12, 2016, 02:30:29 AM
Good to hear its getting put to work. Mine powered our home construction too. The workers were kind of skeptical at first, but they all liked it  after seeing how well it worked.
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on May 24, 2016, 10:47:58 PM
Just a quick update:
The Impco/Garretson/KN regulator has continued to work flawlessly during the last month of regular homestead and fairly heavy construction use.  This is clearly the right regulator for the pulsing intake of the DES 8/1 propane conversion. 

I purchased this $24 (including shipping) 220V AVR from China to replace the failed CGG AVR:

http://www.ebay.com/itm/311412889591?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

This unit is identical the the CGG unit except it takes 220/240 instead of 115v.  It has been working well; 3 volts sag as it gets warm, but that's acceptable.

We noticed right away that the ST-3 is much quieter with a pure 240V load; even the tiny load imbalance to power the 115V old CGG AVR was enough to make it moan a bit, even with new SK bearings.  Jeff's ST-3 (and mine) just doesn't do any load imbalance at all without noise and vibration.










Title: Re: DES 8/1 Propane Conversion project
Post by: Tom on May 25, 2016, 06:24:30 PM
Good to hear things are working well. What compression ratio is it running now?
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on May 25, 2016, 09:36:06 PM
It's running at about 11:1 compression.  With the new gas regulator and leaner mix we might be able to raise that now but the owner is happy with it's operation where it is.

Title: Re: DES 8/1 Propane Conversion project
Post by: cujet on June 05, 2016, 01:56:42 PM
Now that you have it well "dialed in", any thoughts as to actual BSFC, or just fuel consumption observations in general? Do you feel this engine type has an efficiency advantage over a more conventional setup?

Clearly, many people are on natural gas and could use such a setup. Especially if it was a long life, reliable, quiet engine.

Would you do it again?
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on June 05, 2016, 03:11:04 PM
I haven't measured fuel efficiency with this setup, since for convenience it's presently plumbed into the home's main propane tank.  The primary design issues were related to my neighbor's disabilities; he needed a super quiet generator/air compressor engine with no exhaust smells and no gas or diesel fuel handling.   

I would love to have this engine for my own homestead, but the cost of the necessary 8/1 rpm flywheels, carb, new pulleys, regulators, etc. currently precludes that.  The only part of the conversion that was a headache was finding the right carburetor and regulator combination for such a slow speed, gulping intake engine, and finding an appropriately hot spark system.  The spark plug in injector hole was easy.

Natural gas and spark should work with the same carb and KN regulator if desired. NG also gives you the option of running at nearly 85% NG with diesel pilot.  The KN/Garret regulator would be a good choice for that setup, but I'm not sure how to best regulate the gas flow to maximize NG and minimize diesel.


Title: Re: DES 8/1 Propane Conversion project
Post by: dieselgman on June 05, 2016, 04:42:12 PM
In the oil patch... wellhead gas is often available to run the pump jack engines. Supply is often erratic though so sometimes a diesel with the NG as supplemental is used to save on diesel fuel and use a portion of the otherwise wasted gas. Lister HR models seemed to do well with this kind of setup and no spark was needed as long as the diesel was brought up to ignition temps before opening up the gas supply. I think they were only very crudely regulated in that kind of operation with the diesel governor basically controlling engine speed.

dieselgman
Title: Re: DES 8/1 Propane Conversion project
Post by: carlb23 on June 06, 2016, 11:38:02 AM
In the oil patch... wellhead gas is often available to run the pump jack engines. Supply is often erratic though so sometimes a diesel with the NG as supplemental is used to save on diesel fuel and use a portion of the otherwise wasted gas. Lister HR models seemed to do well with this kind of setup and no spark was needed as long as the diesel was brought up to ignition temps before opening up the gas supply. I think they were only very crudely regulated in that kind of operation with the diesel governor basically controlling engine speed.

dieselgman

Thats exactly how i have my 6/1 setup to run.  Pilot diesel and natural gas flow controlled  by a needle valve.  I have mine setup up for 1800 watts with the governor open just enough to keep the engine running.  This is enough electricity for most loads under a backup situation, if demand is higher the governor will open more to pickup the load.  Simple and easy set it and forget it.   I use a electric gas regulator taken from an old radient natural gas heater which is powered by the generator so if there is a engine or genhead failure the natural gas is shutoff by the gas regulator.

Here is a link of my 6/1 on diesel/natural gas
https://www.youtube.com/watch?v=AwPPui8Fyi0
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on July 14, 2016, 06:11:00 PM
One field coil on my neighbor's ST-3 head failed- open circuit.  Much to my disappointment, Tom at CGG does not have spare field coils.  I wondered if anyone had failed unit with a field coil or two they could sell?  I temporarily loaned the whole rotor from my own spare ST-3 head, but I need that back eventually.

There's a few hundred more hours on the  DES propane conversion set and the KN regulator for home construction work.  It continues to perform very well.  We did have to tighten the valve closing spring tension screw on the KN regulator as sometimes we were getting  noticable raw gas leakage out of the carburator inlet during starting and running.   That solved the problem.




Title: Re: DES 8/1 Propane Conversion project
Post by: Tom on July 14, 2016, 09:08:33 PM
Have you checked the connections between the coils. My st5 had a cold solder joint on one of them that opened up after a couple of hundred hours. A little solder in the right place and now 2k hours later all's good.
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on July 14, 2016, 09:34:16 PM
Yes, I removed the open coil from the rotor and checked it separately.  It has a plastic rectangular bobbin and would be very easy to replace if only we could find a replacement.  I'm not interested in rewinding on a volunteer project, though I would if it was mine.

All the other coils checked out fine.  It was easy to find this problem, just measured the resistance between the two slip rings after inspecting the slip rings and brushes, then checked each coil to find the open one, confirmed it after cutting it loose.





Title: Re: DES 8/1 Propane Conversion project
Post by: rosebud on July 18, 2016, 10:48:48 PM
Appreciate the comments on the forum..

Looks like I have a cold solder on a 3kw st head also... It has about 40 hours total time on it....
It was not powering up intermittently...then not at all.
Using Utterpower guidelines... I started looking... Saw a small ohm value across the slip rings.
Moving along, noticed a lack of continuity across one field coil.
After lightly cleaning a small section of coil wires upstream of the small copper connection cap... looks like the solder is highly suspect.

The trouble shooting idea, came from this thread... thanks

steve

ps.. removing the doghouse per UP's mods
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on October 24, 2016, 07:11:53 PM
Bizarre new problem. The DES propane conversion engine is still starting and running fine but has recently developed the serious fore/aft movement of a seriously overbalanced engine.  I checked it over carefully- no lost balance weights, nothing cracked, big end of the con rod looks fine, no slop or play anywhere. For a temporary fix it took 8 oz of lead on each wheel opposite the counterbalance to correct this.

I just can't imagine how it can suddenly be 16 oz out of balance?!

Jeff says the problem has been increasing over the last week, with no other symptoms, sounds or issues.

I'm suggesting that he pull the head and inspect the piston/upper conrod just to be safe.  He has to drain it anyway to put the thermostat for winter morning operation.

Does anyone have any other ideas?


Title: Re: DES 8/1 Propane Conversion project
Post by: dieselgman on October 24, 2016, 07:16:49 PM
Take a good inspection look inside for parts broken or abnormal conditions. Be sure to slowly roll the engine through its full cycle during internal inspection.

dieselgman
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on October 24, 2016, 07:41:18 PM
Thanks, Gary. I did check the crank and conrod big end for a full revolution.  Nothing loose, no problems.  Better safe than sorry, I just called Jeff and he's going to pull the cylinder and head for a full inspection.  I'd like to see valves and piston rings after 400 hrs of run time, too. 

The current oil has 230 hrs on it.  It looks clean as new.  What kind of oil service interval do you recommend for this engine on Propane, Gary?  His typical load averages about 1500 watts so it is not heavily loaded.

Title: Re: DES 8/1 Propane Conversion project
Post by: gusbratz on October 24, 2016, 08:20:53 PM
wonder if a flywheel key could be moving? crank bent? your oil is going to stay a lot cleaner with gas but you may find carbon deposits in the oil and building up on the head, i had one with so much carbon on the head that a big chunk fell off when we were baring the engine around an locked it up. pulled the heads and it was like a pancake in there.  carbon pockets can also hold heat and cause pre-iginition or  detonation. that could be mistaken for balance as it can sound like guns going off in the engine. I would think a light load would be easy on the engine. put a vacuum gauge on the engine and load it up. tune your mixing valve until you have the best strongest vacuum. that is your sweet spot. richen it up just a bit for best performance and elimination of preignition and detonation. or lean it out for best emmissons.  if memory serves i would boroscope the cyl on a 10,000 hour Pm for carbon build up when i worked for the gas company.
Title: Re: DES 8/1 Propane Conversion project
Post by: dieselgman on October 24, 2016, 08:23:55 PM
A normal 250 hour oil service interval is recommended for diesels... but that is primarily because of soot buildup from the diesel combustion. If your oil remains clear, then I would tend to just monitor it closely and change when it starts to change color. One of the nice things about Propane... a very clean burn. One of the major combustion byproducts of propane is water vapor, which also tends to keep the innards quite clean. No need for water injection!  :laugh:

The out-of-balance and sudden-change report sounds like a weird one. Something MUST have moved or changed to allow that to happen!

dieselgman
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on October 25, 2016, 02:55:18 AM
I helped finish the tear down of cylinder and get her inspected and put back together.  Everything looks clean and tight and nothing amiss. Very strange, as the fore aft movement was obvious and I would never have put it in service like that.  So I have no idea why this imbalance shows up after 400 hrs.  A mystery.

Valves look perfect.  So stock valve with hardended seats seems to work.

Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on November 29, 2016, 05:43:17 PM

Since changing to the KN/Garretson type regulator, Jeff says he has noticeably better fuel economy and no running issues.  Unfortunately he has had some very noticeable raw propane smell in the engine room.  A problem for someone disabled with severe chemical sensitivity.  The first obvious offender by stiffing while running was leakage at the carb inlet.  We fixed that by adding 3" tube to an auto air cleaner housing mounted on the wall. Next we found there was a leak at the KN regulator. Internally, there's a sewing type straight pin through the rubber faced disk which seals the gas inlet. The pin head was not sealed. Gas was slowly leaking through and then out of the diaphram chamber. A simple dot of gray silicone gasket maker over the pin head stopped that leak; no more leaking with engine off but gas on. I suspect that parts or material changes over the years may have caused this problem with the KN regulators.

After this we still had a very minor leak with engine running, barely noticeable near the KN regulator.  We traced this to the lack of a gas tight seal on the diaphram to actuating pin attachment; gas was leaking through the diaphram to the vented side of the die cast KN regulator housing.  Fortunately, the vented side of the diaphram has two 1/8 NPT threaded holes. We plugged one, and connected the other to a 1/2" ID hose which we routed into the air cleaner housing.  This eliminated that last of our leaks.  I felt that venting the leak to the air cleaner was preferred over having to modify the diaphram assembly with new sealant and rivets, a fussy job that would have be redone with every new diaphram.

So while I think the KN/Garretson regulator is the way to go for the gulping Lister CS type engine, with gulping intake compatible CA110 gas carburetor, it does need these fixes to not leak gas into the engine room. 






Title: Re: DES 8/1 Propane Conversion project
Post by: dieselgman on November 29, 2016, 06:09:27 PM
Wow Bruce, You sure are persistent and patient! Sounds like a considerable number of small quirks to get worked out. Glad you are managing it so well!  ;)

Keep up the good work and thanks for letting us know the problems and solutions!

dieselgman
Title: Re: DES 8/1 Propane Conversion project
Post by: Tom on November 29, 2016, 08:49:04 PM
+1 for what DGM has to say. It would be interesting to know if the intake valve timing is to spec. Perhaps opening the lash a bit would help the root cause of the back flow of LP out of the intake.
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on November 30, 2016, 07:23:33 AM
Thanks Gary and Tom.   I hope this thread might save someone else doing a low speed (gulping intake) engine conversion some time and trouble, someday.

We did open up intake and exhaust valve lash greatly to avoid overlap and any ezhaust backpressure to the carb many months ago.  This did reduce the gas leakage at the carb intake noticeably and did not affect performance.  Our next step is to take the timing back to stock and see if we are now OK with that using our free MB300D air cleaner.  We have the flywheel marked with the stock intake open and exhaust closed timing events, per 38ac's (brilliant, I think) method, so it's easy to play with the intake and exhaust overlap timing.  On propane at least, the timing makes no noticeable difference in power or running, but our pneumatic valve lifter will have a lot more clearance once we tighten up the exhaust valve lash.

Through all of our regulator work the engine has remained in service and Jeff's off grid house exterior has been completed. All compressed air and electrical power via the DES 8/1 propane conversion engine.  Absolutely no audible noise and no exhaust fumes regardless of wind direction are a big plus for him and his also disabled gal. 


Title: Re: DES 8/1 Propane Conversion project
Post by: Tom on November 30, 2016, 06:02:26 PM
Before you reduce the lash, consider that as it's operating now, there is an explosive mixture in the intake.

I had bought a LP Onan RV generator for backup power at our previous home. It was the good old days when LP was $.61 per gal. In firing it up the second time, I guess the LARGE muffler was filled with the perfect LP/O2 mixture and it went off with a thunderous boom. My 8 year old son about soiled is shorts.

I'd hate to see this happen to an air cleaner full of LP because it will probably be blown to bits.
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on November 30, 2016, 10:08:00 PM
Yes, I'll make sure we don't have any propane in the air cleaner.  It shouldn't be an issue for the small leaks since the intake's big gulps of fresh air will purge it continuously.

Title: Re: DES 8/1 Propane Conversion project
Post by: gusbratz on December 01, 2016, 04:01:13 AM
The stationary gas engines I worked on for the gas company were air start meaning there was an air starter on each cyl and an air distributor to time the air introduction. we would start the engine spinning then once it was up to speed  introduce gas to the mixing valve. once it fired we would shut off the air.  it was like 2 handles attached to 3 way valves and it had the same feel as switching over an old gas start IH dozer from gas to diesel. sort of that satisfying feeling as it came alive.
Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on May 09, 2017, 03:59:22 PM
Just a status update. 
The 8/1 spark/propane converted engine has been running well and strong for the last 500 hours of run time, mostly pumping air for my air table saw and hand circular saw and such borrowed by my neighbor for his home construction, plus domestic duty running the submersible well pump and washing machine. The large diaphram KN (Garret) regulator has been reliable and combined with the large diaphram CA110 carburetor (thanks Gary) is the solution to the "big intake gulp" of the Lister CS clone.  No more leaking gas smells since we added an old MB air filter and housing and connected the regulator vent back into the air cleaner.

I'd convert over my own engine to propane except I'd need new flywheels to do it.



Title: Re: DES 8/1 Propane Conversion project
Post by: veggie on July 12, 2018, 07:43:28 PM
BruceM

3 questions regarding the conversion...

1] How were you able to get a negative inlet pressure in the intake manifold in order to activate the propane regulator?
Does the stock diesel valve timing produce enough vacuum or did you have to alter the valve timing?

2] Are you still using the compression release to start the engine? or do you crank it under compression like a regular gasoline engine?

3] Did you lower the compression ratio ?

Sorry if this was discussed earlier, I must have missed it in the previous 15 pages  ;)

cheers,
Veggie



Title: Re: DES 8/1 Propane Conversion project
Post by: BruceM on July 12, 2018, 08:07:06 PM
Hi Veggie,
1. I used a CA110 propane carburetor.
2. Still use the decompressor for starting since we're using a relatively wimpy Gast 4am w/rubber roller starter.
3. Yes, the compression was lowered repeatedly to where we had no knocking at full load. A total of 0.6 inches of aluminum spacer and gaskets. I believe we could have a bit less since changing to the Garret KN type regulator. That regulator also make the carb rich/lean adjustment work properly.  To accomodate the 0.6 inches of head raising, I added to the length of the shorter pushrod, and moved the longer pushrod to the shorter position.

Yes, all this is covered in the prior pages.

The engine has logged around 700 hrs so far, and has been problem free.  The oil stays in pristine condition, looks like it just came out of the can.  Mostly it's running the air compressor for construction projects, plus generator (ST-3) for well pumping while running the washing machine.  Someday I'll get my air skill saw back. :) 

I'm happy with the result.  My health and enthusiasm for non-essential projects is waning or I'd do mine.  My neighbor is happy to not be hauling and handling diesel fuel.  It's pumped into his main propane tank which serves 15psi gas to the pex-like plastic distribution lines, down regulated at the engine room, shop and house to 10 inches of WP.