Farmall A Series Cylinder Compression Ratings

dunniteowl here again and I have gotten the "A" model I have straightened out as far as the cylinder head and torqueing goes. I am getting spark, fuel, air and compression, though I wonder if my compression levels are high enough to combust.

So, does anyone have the specs or the skinny on what the nominal compression values ought to be?

Currently, Bettty's compression values are as follows:

Cyl 1: 72 pounds
Cyl 2: 60 pounds
Cyl 3: 61 pounds
Cyl 4: 71 pounds

do these numbers sound about right to anyone or no-one at all? I have a maintenance manual (bought online through your suggestions) and it doesn't have any compression specs in it that I could find.

Thanks all for any information and assistance you can provide...

dunniteowl

During that time there were a few times I tried to check compression without the rocker arm assembly installed. I know, stupid thing to do, but ultimately, I figured it couldn't really hurt as the pistons don't go to the top of the cylinder sleeve and the valves don't depress anywhere near the top of the cylinder wall/sleeve. Also I realize the cam-shaft is mated to the crank from below and not having the rocker arm assembly in place on top should not have any net negative effect. I am sure this could be wrong, but it logically seems sound from the perspective of construction.

I do believe, however, that this could seriously affect the timing and again admit I am happy to be wrong about that.

I am going to try the gas in the cylinder trick and if that doesn't do it, I will indeed be making sure the timing is set the way you suggest. From there I am sure new information will be coming.

Once again, thanks for the tips and I will be posting new stuff as soon as I have daylight, dry ground and no other distractions (I have no garage or actual workspace for my tractor and I just have to 'rough' it where she currently is in the yard -- which is growing ever higher as I attempt to satisfy the conditions that will get her to operate again.)

Dunnite, isn"t this the tractor that was spitting oil out the stack after you perhaps poured transmission fluid into the oil by mistake?

Yes, this tractor will run with those readings. Someone (I forget whom) is fond of pointing out that they had a flat-head Ford V-8 that was winning races with 40 lbs. in each cylinder!

But, in that famous instance, the compression was low but the differnce between cylinders was not great.

I did the math, and came up with a seventeen percent difference between the highest and the lowest compression readings. That may be only marginally acceptable.

The "wet" readings may be somewhat better. Compression testers are not completely accurate. And, a compression test itself is not the final authority.

Nevertheless, it is my personal belief that if the gasket is now correctly installed, the valve train is functioning correctly, the plugs are all seated correctly, etc., and these are accurate readings, you are headed for a rebuild sooner or later.

Also, you"ve named this tractor, which leads me to believe you are fond of it. If you don"t already know, delaying a rebuild by continuing to run a worn engine can lead to more extensive and expensive damage.

Finally, there is a frustration factor. Again, the tractor will run with those readings. It may be quite hard to start, though.

And, will it pull well enough to run a mower? You won"t know until you get it running and try; and my personal belief is that it will only pull well enough to cut thick or high grass if you make half a swath on each passage and stay in first or second gear. Very frustrating.

If the cash is available, consider plunking it down for a rebuild now. If not, start saving.

Hal? Jim?