DES 8/1 generator build

[38ac]

the clearance is right where i want (.075-.080 for aluminum piston).

The bump difference between the 6/1 and the 8/1 are due the lack of a compression change over valve in the 8/1 and have nothing to do with the piston material.  

Having machine tools handy is a big plus when working on a 'roid. I have a shop full of them and when engines leave my shop they are made as right as they can be made. However my advise here to the do it yourself crowd  is always pointed towards what must be fixed to have a reliable engine and what can be left alone. Not many are interested in a cost no object "make it perfect" engine if you get my drift?  I just dont wish to come across as suggesting you are wrong in perfecting whatever you can on your build,,  I also have some concern that people reading my posts would take them to mean that I advocate sloppy craftsmanship as I do not.  I do try to separate myth from fact,  what must be done from what can be done. And what is a waste of time, effort and dollars.
 
Back to your cylinder block and what I would do if it at my shop.
How cylinder blocks are checked and trued  depends on what work the bore needs.
Any India or Dursley block with a new or usable bore I use the bore as the starting point.  A mandrel is chucked in the lathe and the bottom is then checked with an indicator. Run out less than .005 is  called good. Where did that figure come from? By checking Dursley blocks. Actually I no longer check the bottom of most Dursley blocks, they are assumed to be right UNLESS they have been frosted.  Once the bottom is checked and made square to the bore the block goes to the horizontal boring machine and into the fixture I use to bore the cylinder. The deck is trammed with an indicator and if needed a light cut is taken true things up.  If the block is to be bored and sleeved I skip the trip to the lathe and bolt the block to the fixture and preform all the bore and top deck work using the bottom as the beginning reference point.  You can do all of the top and bottom deck work on your lathe using a shop built mandrel and some creative tooling. I use the Ho-bore for the top because it is easier/ quicker than doing it in the lathe.

[BruceM]

I'm confused (my usual state lately), and I don't get less so searching old posts on bump clearances.  The Listeroid and clone 6/1's with no changeover valve are spec'd with 0.045-0.050 bump, I think. The only difference I"m aware of for the 8/1's are the aluminum piston and rpm.

[38ac]

Bruce,
That's because there has been some pure bunk posted about the subject and add to that  the Indians deciding to mess with the plug design for reasons only they know. Easiest way to come to understanding is to forget 6/1 vs 8/1 as rated HP and RPM or piston material has no bearing upon bump spec.    The compression ratio for a CS is the same with the plug (at least the plugs that match OEM which includes the DES clones) or the change over valves screwed in. Lister increased the bump on the plug equipped engines as a compromise between the starting compression ratio and running ratios on a COV equipped engine. The actual numbers are on the spec page on my build thread. Lots of the engines were, are are still  run with the COV turned in and never messed with. So the unanswered question in my mind is this, Is the increase in bump necessary? Cant say for certain but it stands to reason that it would be less stressful on the inner workings.

Butch

[38ac]

This is an oops

[BruceM]

Thanks, Butch! My older Metro 6/1 is one of those Listeroids with the non-Lister plug design which allows them to spec 0.050.

I'm beginning to see the wisdom in DES's choice of Lister or Lister clone only.

 

[gusbratz]

well i dont' know if i am on the right track. I may be splitting hairs here. i have never measured all this stuff on any of the lawnmowers, dirtbikes, gravelys ect i have rebuilt. just sort of bolt the jug and head on and never even thought about it. so i don't feel like I have a baseline to say "shit i've seen worse" LOL. plus I  been on night shift for the last 10 days and now I am on my 5 day off.  gets to sort of feeling like a zombie and the brain does stupid things. long story short i just put it together and am going to run it. here are some measurements i took. i am not a machinist but i play one on the weekends.
i measured the length of the new cyl and it was within 1 or 2 thousands of  being paralell with my big dial calipers, I would call that good. then i  put a little surface plate on my mill (because the table is pretty beat up) and tramed the mill. sort of neat to see the plate is warped like a bannana. 0 in front 0 in back +1 left +1 right. stacked the cyl on it and did a runout on the base (with my good dial that reads out in tenths of thousands). it was within a thousands. then I set the dial up in a bar and went as far into the cyl as the mill would stroke. got 0 left 0 right, +.005 front -.005 back. I would call that off square.
I then measured the length of the old cyl with the big dial calipers. it was off .008 like the base was at an angle, or warped.2 corners were the same 2 were off.  then i  did a runout on the base as before and it went up and down and up and down. then I stroked into the cyl and it was friggin perfect! withing .00005 on all 4 sides. if i could just bolt it down upside down that one would run sweet. unfortunaltly it has a weird base. just for kicks i put the old cyl on the engine and measured the bump. with one .020 base gasket i got .088 front .080 back. judging that the new cyl gary sent me is only off by .005 front to back, vs .008 on the old one plus the pin hole i chose to run the new cyl. i am pretty sureif i tried to true it up in my lathe it would be a mess because i struggle to grind nice tools. surface quality of everything i touch is shit.

[38ac]

Re your surface finish problems when preforming machine work.
Speeds and feeds simple as that. Most beginners tend to run way too slow and too light of a feed rate and too shallow depth of cut because they are afraid of getting too deep. The only way past this is practice practice practice.  You simply must push the feed speed depth of cut envelope in order to achieve a decent finish in most materials. You must of course have a decent tool but a perfect tool will not finish if not pushed right.  Cast iron is more forgiving in all respects.

[gusbratz]

what size hoses do i need for anatural circ cooling system, i have a 5 core 24" tall cast iron radiator about 4' to the left and 12" above the  engine sitting on a shelf. I cut a hole in the wall behind the rad and plan on putting a 120v ac fan on it hooked to a 210*F thermostat that will kick on if the radiator cant keep up.   i have all the stuff on hand to do 3/4 heater hose. that is what size the flanges are. i allready intstalled a 195* thermotat. I guess i could run it that way and see if it heats up then up to 1" if I have to.

[dieselgman]

The actual dynamics of your cooling system will vary significantly with the engine loading and the environmental variables. So you will no doubt find experimentation useful in your own setup.
Lister designed these around tank convection with 1" hose, and fan forced radiator cooling with slightly larger about 1 1/4" hose. We have seen a very wide array of successful cooling arrangements with all sorts of smaller hoses as well. Of course, BTU-input must equal BTU-output to reach and maintain a stable operating temp equilibrium. Sufficient convection circulation of the coolant might be a bit more difficult to achieve if you depart much from the hose sizing as well as tank size and position configured by Lister, but your radiator sounds like it will work fine. The thermostat is another item that Lister did not use on these engines... but many have good results with a 195 F stat - (some with minor weep-hole modifications).

dieselgman

[BruceM]

The vertical is important for themal only driven flow, as well as temperature differential.   Is the bottom of your radiator to be 12" above the valve cover?  I'm assuming so for this assessment.

I did a convection system for my neighbor's 8/1 propane unit.  We had to go to 1" hoses, and raise the triple row "racing" Honda Civic radiator plus raise our 16" hot air stack to 8 feet total with wind turbine.  The backup fan now runs only on very long sustained full loads on dead calm summer days.  His radiator (bottom) is 24 inches above the valve cover.

We had previously done 3/4" heater hose, and that was just too restrictive for our wimpy thermosiphon flow. 

Your backup fan will solve the temperature differential issue,  and that MIGHT let you get away with 3/4 hose.  We were doing double convection; both for air and water.  I hate redos myself so I suggest raising the rad as much as you can and going 1".

Best Wishes,
Bruce

[Hugh Conway]

@Gusbratz

We are using a 10 rib cast iron radiator, no thermostat. 1 inch hose. Seems to work fine for the last 2 years, about 600 hours run time.
I also have a thermosiphon water heater and coil attached to my wood stove to provide winter domestic hot water.
There again, I am using 1 inch diameter (copper pipe rather than the rad hose on the listeroid)

I would also recommend that you go with 1 inch. for a thermosiphon system, a larger diameter pipe provides less internal friction, water circulates more easily. Vertical distance and no downward flow is a must for thermosyphon to work efficiently.

Cheers,
Hugh

[mike90045]

I use 1" hose, upper and lower, a thermostat, and a 30 gallon tank, and passive circulation works OK.

[gusbratz]

thanks for all the responses, i will just go straight to 1".

[gusbratz]

progress has slowed to a crawl on the engine, been kind of bouncing from fuel to cooling to exhaust while i wait for parts in the mail. I got the exhaust done last night. a 1-1/2 swept elbow to 2" swept elbow going into 3" piece of conduit. all scrounged from work. i did buy a little 1-1/2 flex and weld into the 1-1/2 pipe. where the 2" goes into the 3" i had to slip it in and weld it so i drilled a bunch of holes in the 2" before i slid it up in there.  got a neat little chimney cap from the neighbor and put on top of the tail of it all. can't wait to see how it sounds.   i sort of worry it's going to be like a big megaphone. that brick floor was the best idea i have had in a long time, lets me just lift up bricks to run stuff under the floor.

[mike90045]

you may need more flex, or maybe the conduit is softer then water pipe and will soak up some.

Love the red cap !