Started on another Listeroid rebuild today. This time a twin and a other odd ball mixture of parts. Tag says GM90 but nothing is different than regular twin. Also rated at 22HP at 1000 RPM but has cast iron pistons, that's scary. Engine has either been outside during a hurricane or been under water as it was full of water to the crankshaft.
more pics
parts pile
Quote from: playdiesel on August 02, 2020, 06:08:53 AM
Started on another Listeroid rebuild today. This time a twin and a other odd ball mixture of parts. Tag says GM90 but nothing is different than regular twin. Also rated at 22HP at 1000 RPM but has cast iron pistons, that's scary. Engine has either been outside during a hurricane or been under water as it was full of water to the crankshaft.
To be safe, it might be best to limit RPM's to 650. That is a whole bunch of mass the crank is throwing around inside the block.
All the GM90's I've been around have aluminum pistons and were direct injected. Their might of been a mixup tagging the engine after it was built. Its been so long ago but I believe the oil pump is inside the block that runs off the crank, all had tapered roller bearings and had counterbalance weights on the crank. I could be wrong, I believe the GM90 crank was drilled to pressure lube the large rod end. The oil dipper functioned the same as listeroid's. And, served as a backup to help lube the large rod end lubed in case of a pump failure.
Henry
ya there is no way that cast iron is good at 1000 RPM. One thing I have learned from going through a bunch of these is never assume anything with a Listeroid
I think I would hang it up if I still had to clean
parts by hand. Parts washer uses an alkaline detergent and works at 180F. Grease and oil disappears instantly and loossens up the India paint and putty so it falls off when dry.
block and other parts out of the washer and ready for more prep work.
Quote from: playdiesel on August 02, 2020, 09:00:59 AM
ya there is no way that cast iron is good at 1000 RPM. One thing I have learned from going through a bunch of these is never assume anything with a Listeroid
The RPM would depend on the offset of the counterweights in the crank or flywheel. Iron pistons are not that uncommon and just throwing in an ally one might cause a LOT of imbalance.
Don't rush in with presumptions, make sure what the thing is set up for because it's more than likely it WILL run to 1000 RPM very smoothly and putting in an all piston will turn the thing into a Jackhammer if the flywheel or Crank counterweights are then too heavy.
Very early on in the 8HP, or 8/1 program Lister encountered serious problems with over stressed parts at 850 RPM. Realize that its not a matter of it flying apart the first time it hits 1000 RPM. Lister warrented its products, as do I while India does not. By Lister standards the life of certain parts was short at 850 RPM. This involved the con rod and both big and small end bearings and also the govenor. . Lister solved the issues by changing the pistons to aluminium and using a bimetal upper shell for the big end which allowed them to continue on with the 6/1 con rod. They also changed the upper shell to the bi-metal one designed for the heavy flywheel 6/1 engines. They also lightened the governor weights so that a lighter spring could be used and still have 850 RPM. This engine has 120MM bores thus the pistons are even heavier than an 6/1! This will be a work engine at an off grid installation and customer has been advised to operate at maximum of 650 RPM or to change over to aluminum pistons and run at 850 maximum as per Lister engineering work preformed many years ago. These engines are short lived at 1000 RPM no matter what componants are used, I don't recomend. 1000 rpm operation because Lister never did, a presumption as you will.
You are correct about balance. I have never seen a properly balanced Listeroid thus all through the shop are rebalanced anyway.
Quote from: playdiesel on August 02, 2020, 09:00:59 AM
ya there is no way that cast iron is good at 1000 RPM. One thing I have learned from going through a bunch of these is never assume anything with a Listeroid
I stand with you on this, especially when we're talking about listeroid engines. I've seen some pretty bad flywheels that came from India. (Spoke and Stover style) casting defects are covered up with filler, not balanced properly, sloppy machining of crank center hole and key way. I've seen listeroids run with a pretty good wobble and some where the center hole was off center. The iron grade used is questionable.
When I purchased my 6/1 GM90 Mike Monteth and I went through many spare flywheels he had in his warehouse before we found a set I felt comfortable with. Since the 6/1 GM90 is internally balanced I went with the heavier, smaller diameter stover type flywheels for an extra margin of safety.
Its best to keep speeds down to lessen the chance of a flywheel explosion or something else coming apart.
Here is something: https://listerengine.com/smf/index.php?topic=115.0
Henry
Casting prep consists of a thorough interior sandblasting a d a quick exterior job. Followed by a needle scaler and lots of picking to remove slag and sand pockets. The inside gets a coat of a Gyptol type product, outside is primed and lots of sealing surface prep.
Setting the crankshaft up in a twin is a bit tedious and India often screws it up. The center main housing is retained by one bolt with a lock nut. You do NOT tighten that bolt! It is snugged against the housing and retained by the lock nut. The center main must not be used for trust. The outside bearing housings must be shimmed so as thrust is taken by them.
Picture shows a main bushing with destroyed thrust surface due to improper end play.
To properly set up a twin crank with bushing mains a person realy ought to have an indicator but in a pinch a trained eyeball will work. You first set the crank and secure the center main housing. Then measure total end play, it will be a lot. For the example here I will say .100". Then you divide by 2 and subtract .005. Sorry for being so wordy here but I can't be any more simple about it, it will make sense in the end, I hope. In the example the math would be .100÷2= .050" minus .005 = .045"
Now to set the bearing housings and end play properly you set one bearing housing, either one, and adjust the shim pack until end play is .045". Now set the other bearing housing and set end play at .010". If I haven't confused everyone what I have just done is set the end play at the desired .010" and centered the crankshaft in the center bearing housing. I have never seen a roller bearing main twin but if such things exist the procedure would be to set end play exactly .000, no slop, no preload while at the same time centering the crank in the middle main.
People often ask is it realy necessary to take a Listeroid all the way down?? The answer is of course not,, how's your luck at gambling? So far as engines that I have personal knowledge of the only India engines that gave no trouble are the ones not ever used. One of the more common issues is the oil pumps. If your engine has an oil pump and actually needs one, which would be any bushing main engine and all twins. Then I consider it mandatory to take the pump all the way down and fix the ball seats, defective springs, bad seals etc. The other issue is rust. I see a lot of NOS engines such as this twin that were imported 15 years ago and not kept in best storage. This pump would have pumoed zero oil if not repaired and with no guage to tell you it isn't operating good by main bearings.
A weekness in any twin is the #2 pump cam has zero lubrication. This is not strictly an India problem, Listers have the same issue that must be addressed in work engines. There are several ways to do it, this is how I fix them. I drill a 1/16" hole through the rotation stop screw. Then drill deep enough to tap at 1/8"npt and add fittings and valves as shown. The feed line valve is only slightly opened. Also shown is a pressure gauge and snubber valve. The oil pressure pulses with pump operation and is very hard on guages. I use a needle valve to snub the pulses and a quality liquid filled guage. However a person could get by with a cheap guage and a ball valve. Once the operator has verified oil pressure at start up he then isolates the guage with the valve. There are many variations of the top plug in the pump, some are blank. I drill and tap the blank plugs to a 1/4"NPT , The ones with the additional plug such as the one pictured are drilled out to accept a 3/8" NPT tap and then bushed down to 1/4
The oil inlet screen,, more reasons to assume nothing with a Listeroid .
:o ::) Wow! That picture definitely enforces the reasoning to tear an engine apart if your not sure of the condition of the engine from sitting outdoors all those years.
Cam failures were not uncommonly reported on India twins and some originals. Do you think that was due to cam shaft warping from cam pin installs with resulting stresses, or some other cause?
I love this simple fix for the twin dry cam.
The cam drive on a twin is identical to a single and has over double the loading and twice as many lash reversals every revolution, short life should be expected I think? The camhaft is the same diameter, operating twice as many valves, twice as many fuel pumps AND driving the oil pump. I have no means to measure torsion but can offer a guess, Lots. On paper I have designed a single cog belt drive for singles and dual cog belt drive for twins but it will likely never see the light of day due to lack of engines that actually get a lot of hours on them.
Stacking a twin Listeroid is complicated by loose fits and tolerances. If not down right You will have leaks and can also break the manifolds. After squish is set and before the heads are torqued down I install the water manifolds and just snug the nuts. You want them to hold the cylinders square let allow some up and down movement as the heads are torqued. You must torque both heads in sequence I start at 25 ft lbs and every 25 to 150 on the four big studs.