1937 John Deere A Rebuild

I appologize if this topic has been brought up a few times before (as I'm sure it has), but I have a few questions regarding the project tractor that I have started on recently.

The engine was loose when I bought the tractor, but it would only turn about 1 revolution of the flywheel and would get tight again. No problem, I figured some junk in one or both cylinders. So I pulled the head, and one cylinder looked pretty good, the other cylinder was a little rough. I went ahead and pulled the block and began honing to try to clean up the cylinder walls some. How bad can the pitting be on a cylinder and still be usable? The pitting is near the top of the cylinder.

Also, when I took the pistons out, both oil rings are broken. I haven't measured the rings to see if the rest are in good shape, but if they aren't, can I buy just the oil rings somewhere, or do I need a whole set of rings? This is a budget tractor that is quickly heading toward over-budget, and I'm trying to keep some costs down.

The last question I have is in regards to the pistons. The engine has been overhauled during the past 73 years, and the pistons are aluminum .125" overbore. Can someone give me a height measurement to tell if they are high compression pistons? Is there some other way to tell?

Thanks,
John

Try to find the reason the oil rings were broken..if you can.
Measure the Gap, between the ring ends when installed near the bottom of each respective cylinder..(the Least-worn end of the cylinder..
If it is more than 1/8" you NEED new rings..
(1/4" is not uncommon to see.), and should be much less than the 1/8" I mentioned..
Did you have much of a Ridge near the top of the cylinder..?
Pitting Above the point the rings stop of is no consequence..
Below that is hard to say..NO pitting would be best...severe pitting and it should be bored.
Hone evenly..all the way to the bottom..the rings wear at the lowest point that the rings travel at the point the stop..
If your light is right, you will see that..
Contact JDBPuller for advice..
Hastings (and others) will have the rings you need.
I would advise you to be sure they are NOT Cast rings..Nodular Iron will not shatter like cast rings..
Do what you can..I am sure it will turn out well for you..even if you have to just replace the oil rings..

If you pistons are aluminum and .125 they are the high compression. there should be indentions on the sides at the top for the plug to fire. If the pitting at the top and is not too bad it will be fine. Just hone enough to get a good cross hatch, check to see if there is a ring groove at the end, you may not have one since this tractor has been taken out to .125 and install new rings.

Thanks for the help. Two cylinders are still kinda a mystery to me still.

There wasn't a large edge at the top of the cylinder, but there still is one. I got it honed tonight and will put it back together and see how it does as is. If I need to, when I have the money I can redo it.