Farmall 140 compression a tad high

PretendFarmer · Dec 4, 2013

1960 Farmall 140.
Last winter I rebuilt the motor. Had the head completely redone. Cylinders 2,3, and 4 were fine. I reused the pistons and just reringed them. #1 required a new sleeve, piston etc. 2,3, and 4 are firecraters while #1 is that new stepped head piston. My compression on 2, 3, and 4 is 150psi hot while #1 gets up to 175psi. That seems high. It runs fine. Any concerns?

old · Dec 4, 2013

Running like that can/will break the crank shaft or some other parts. An unbalanced engine is not a good thing to have

Bob · Dec 4, 2013

I agree it's NOT an ideal situation, but I think saying that it will break the crankshaft is a bit dramatic!

The weight of the pistons (should be equal) is MUCH more important than individual cylinder compression.

And he did NOT post the weights of the pistons he used. Even though the CR is different the WEIGHT of the pistons MAY be the same... or NOT!

The other factor would be if the higher-compression cylinder pre-ignites with the gas being used and the load on the engine.

About 20 years ago I got an SBC Chevy 350 block from a machinist friend that had 2 cylinders bored .060" OS, and the other six standard.

We put it together with 6 OEM pistons and 2 aftermarket OS pistons. We weighed them and all 8 were darned close in weight even with the different size and manufacturer.

Some "experts" said it would shake like a *@&#^$%. Others said it would be OK.

It was. It runs about as smooth as any other run-of-the-mill SBC.

I still have the old pickup and it still runs.

(NOT saying what we did is good practice or that the engine is as smooth as a "blueprinted engine", but it did work OK for our non-racing purpose!)

old · Dec 4, 2013

I have run into more then one broken crank shaft and the first hurt badly as in it hit my foot and I found mis-matched pistons in that engine 60 VW by the way

Bob · Dec 4, 2013

<Mis-matched by weight or C/R?

old · Dec 4, 2013

???????????????????????????????????????????????????????????????????????????????????????????????????????

Anonymous-0 · Dec 5, 2013

I wouldn't worry about it. There has been a lot of engines that ran a long time with low, if any compression on one hole that didn't break the crankshaft. Just don't drop it on your foot!

PretendFarmer · Dec 5, 2013

Well perhaps I'll consider replacing the other 3 pistons. I don't run this thing whole hog, while using the tractor I'm usually around half throttle. Runs very smoothly.

rustred · Dec 5, 2013

bob, you are correct, oversize pistons are made to equal the weight of the original piston size, and will hurt nothing.

Janicholson · Dec 5, 2013

If it is not vibrating leave it alone. The real issue is piston weight, as the crank has no ballance weights, the rod/piston combo are matched (two up and two down) thus their weight is smoothing the engines inhearant ballance issues. They are probably just fine if no noticable abnormal vibration. Jim

Farmall 140 compression a tad high

PretendFarmer

Well-known Member

old

Well-known Member

Bob

Well-known Member

old

Well-known Member

Bob

Well-known Member

old

Well-known Member

Anonymous-0

Well-known Member

PretendFarmer

Well-known Member

rustred

Well-known Member

Janicholson

Well-known Member

Similar threads