Cam Idler Gear Problems in Twins, and dry IP cam

[SHIPCHIEF]

I moved some of this over from 'single vs twin'
Some people think the Twins have more cam gear train failures than singles. I was looking at the original Lister manual, My ASHWAMEGH, and Rocketboy's pictures of his LOVSON.
Cujet was talking about poor lubrication to the left side injector pump cam lobe, and I mentioned my oil system mod to oil it.
"I think the oil pump has plenty of capacity, because the oil distribution manifold (above the crankcase door) has pads for five oil discharge tubes. My engine only uses three (one for each main bearing) the other two were originally used by Lister to fill oil troughs for the con rod dippers. On Rocketboys Lister pages you can see a picture in his crankcase with two tubes going straight down. These must be unused as trough fillers, because his sump does not appear to have troughs. It does unload the oil pump though. I wonder if the Ashwamegh cam gear failures are caused by oil pump overload, because these two tubes are not drilled / installed, so the oil pump has 40% less cross section of discharge area?"
  I think this could cause a high pressure pulse on the cam gear train, particularly when the oil is cold. The solution would be to add a bypass oil filter on the oil pump discharge, and put a control orifice in the filter inlet. The filter discharge would then be directed at the 'dry running' left side IP cam. That would cure two problems with one mod.
I got a Motor guard toilet paper filter for this, and my next step is to plumb it in with an oil gauge that is sensitive enough to show the oil pump pressure spikes.
Scott E

[Joe]

On the oil pump capacity…I’ve done a few calculations because I’m in the process of fitting up an external oil filter (off topic for now).  I measured cam lift (.4”) which is plunger travel…. Pump plunger diameter (.625) and get .12272 cu in per stoke…multiply by 325 (half engine speed) and get 39.884 cu in per min or .172gpm or .653 liter per min or to make it all easy a bit better than two and a half cups of oil per minute.  This is of course assuming 100% efficiency of the pump and we all know what we get when we assume….
Numbers were derived from a typical 6/1 pump YMMV…..


Joe

[SHIPCHIEF]

Joe;
Does your 6/1 have an oil pump and roller bearings?  The PowerSolutions single I looked at did. The oil pump directed two fairly large tubes at the TRBs. I didn't get the impression that there would be a  serious restriction of oil flow that might overload the pump / camshaft.
I selected a PH8 spin-on filter and bought a filter head from NAPA. I chose these because the PH8 is about the most common filter around, and frequently on sale too. Because you have an oil pump, you can pipe the oil up to the cooling water outlet and use it to heat the oil. Then run it thru the filter, and back into the engine. I used a marine oil cooler and it works great.
I'm thinking about Twins because I have one that runs at 1000 RPM. Lubrication is more of a problem with these, and the 1000 RPM really pushes this design to the limit. (my opinion).
The oil pump does not have a relief valve to protect the cam drive from overloads.  The discharge of the pump needs to be free of restriction so pressure won't get too high at rated speed with cold oil. (Unless the oil is too slow to fill the plunger cavity, then you just get less oil flow to the main bearings)
The point I was making about Twins and oil pump discharge tubes was intended to get some twin drivers to look inside their engines and notice if they had 3 or 5 discharge tubes on the distribution manifold. Also perhaps the size of tubes?
JohnF13; what say you? Do your twins that have good cam gear history have 3 or 5 oil tubes?  Rocketboy; what say you? Do your new twins have 5 oil tubes?
I'm trying to see if there are other possible causes of cam gear failure...It may be simple cost cutting in India, both cheap gears and pump overload?
Scott E

[Joe]

Scott,
Yes, I have a Power Solutions 6/1. It has an oil pump and TRBs on the main shaft.  The idler gear fits well with no backlash however it is not the new bronze unit that I believe someone said they had in their 12/2. I don’t know the details on when and which PS engines are getting the bronze gear.
As to your filter HP8= small block Chevy etc. I have a shelf full of them that I use a lot however, the HP10 that I plan to use is smaller and I need smaller to fit it between the wheel and the base right under the TRB housing.  There is a picture of what I plan to do on the OSL web page. The HP8 rated flow is 10gpm while the HP10 is only 8gpm…funny how the numbers run… Both have internal valve relief rated at 22psi for those cold startups you are talking about. I’d be surprised if the stock pump could get the pressure that high.  As the cam drives both the oil pump and injector pump not much can be done to it to increase volume of oil per stroke…however, a larger diameter pump plunger would do it but at an increase in load on the drive gear…  No free lunch here…..

Joe

[JohnF13]

Hi Scott;

In my twins I have had catastrophic cam failure, but I don't believe it was in any way due to the oil pressure.  The first one, a Vidhata, broke the camshaft itself where it goes through the cam gear.  Later inspection found that the pin had been drilled WAY off centre, causing first the narrow side to crack then the other side.  The 25/2 Ashwamegh  - well, that was the infamous cheap gear train issue.

I have noticed in the older twins I had there were two oil pressure relief tubes leading back into the sump - they were always in the way when you needed to access the sump through the inspection port.  On my newer engines (JKSon's) there are no such tubes, so there are only 3, one going to each end bearing and one to the middle.  I have not had problems with that setup yet and don't think I will - I really don't believe (again, haven't measured it so I don't know for certain) that the oil pressure is strong enough to cause a problem with a 1" piece of steel that is supported every 15" or so.

I'm open to correction on any of this if anyone has some hard data!

[rsnapper]

I'm considering a power steering pump like mentioned in another post to take suction on the tee in the sump. Then route it through a filter and then to the injector pump covers. I think it should be adequate flow to lube the IP cams as well as filter the oil. Is this a viable option? Would it also be enough to suplpement the stock pump or even replace it? Shipchief, is that what you have done?

[SHIPCHIEF]

rsnapper;
When I had the engine apart to remove the sand and dress the crank, I built a new oil pump discharge pipe and used bulkhead fittings to pass the oil out of the engine. I used 3/8" brake tube, and fuel hose to send the oil to a boat style oil cooler I mounted in the hot water up-leg. I did that to heat the oil because Hotater said his oil runs about 100 degrees F, which is too cold to drive moisture out of the oil.  Then the oil went thru a NAPA spin on filter base with a cheapo Fram PH8 filter, then back into the engine and thru the original oil manifold and squirt tubes to the main bearing drip troughs.
I drilled the left side Injector Pump cam cover 1/4" pipe, and brazed up a short piece of very small brake line to a 1/4 pipe -to - hose fitting. After assembly, I bent the tube to direct the squirt of oil onto the cam lobe where the roller tappet meets. The right side IP cam gets plenty of oil off the cam gear train.
I got a toilet paper cartridge oil filter (motor guard, no commercial interest etc.) and plan to plumb it into the fitting on top of the oil pump ala George B's CD, then send the clean oil to the oil jet I made for the left IP cam. If the oil flow is too great for the drain hole, I can restrict the oil flow, or Tee some off to the bolt hole over the left side cam bushing, where you are supposed to drip some oil when you oil the rockers.
I haven't figured how to oil the rockers automatically yet....or if I want to.
About the power steering pump; Kradawg mentioned that honda pumps were well sized, cheap and easy to adapt.  I just wanted to avoid the extra parasitic load, and besides, I was having so much fun! If you have a Listeroid single without an oil pump, that might be the way to go for oil filtering and temperature control.
Scott E

[cranelift]

shipcheif said--" and my next step is to plumb it in with an oil gauge that is sensitive enough to show the oil pump pressure spikes".
Hi Shipcheif, Want to watch the oil pressure spikes, OK, but maybe  not for long. I read somewhere  that the listers with an oil gage had a shut off valve in line with the gage because the pressure spikes will kill your oil gage. And it doesnt have to be a sensitive gage either.I have a gage on mine (0psi -30psi) and it really slaps that needle around too, not a pulse at all, but a SPIKE.. Just open the valve to check pressure and then cose it off. No beating up on your oil gage. (a gage failure would pump oil out, no?) Have fun be safe

[cranelift]

Hey, I just thouhgt , maybe the oil filter and it's housing will smooth out the pressure spikes on the oil gage. When you try it could you pass on the result. 

[rocketboy]

just an observation here but the oil temp seems to run very near to the temperatue of the coolant entering the lower cylinder jacket. Makes sense if you think about it.

[BobH]

Rocketboy. How about a 120 volt engine heater for aircraft engines. Not a lot of draw, self regulating etc.

BobH