1940 JD B Cylinder scoring

Le9102011 · Nov 5, 2019

Hello all. I just picked up a project tractor in pieces, and too my surprise 99% of the parts are there. Head was machined flat with new valves and guides but the block dosent look like its been touched by a machine shop. Took the block in today to have it measured, and it maybe has .002 of taper on a .45 over bore. Machine shop said that there is some rust pitting in the bore, along with some scoring, he said that he is going to run the hone through the cylinder to clean the rust out, but recommended that I bore the cylinders due to the scoring. It isn't terrible and im not all that sure that it will hurt the engine in any way since it is a low compression low rpm engine. I don't want to trash a good set of pistons if I can get away with it, any advice would be helpful

Mike M · Nov 5, 2019

I guess I'd want to see it after it is cleaned up and then figure out if I could live with it ? Going to be hard to find pistons for that. Likely will need sleeved back to the pistons you have if you go ahead and do it.
I had an unstyled B that started up really nice and seemed to run fine, but it would blow oil droplets out all over from the exhaust ! This tractor was to be resold anyhow so I did not touch it.
I later talked to the guy that got it and he said the piston pin came loose and really scored up the cylinder. I do not know if he even fixed it ? But they must be able to be pretty bad and still run fine.

1940 JD B Cylinder scoring

Le9102011

Member

Mike M

Well-known Member

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