John Deere High Comp Pistons

PullinDeere

New User
Does anyone know where I can get a set of high compression pistons for my 1940 B I can find some for later models with the 4.6875 bore but not for the 4.5. Or would it be safe to bore it that much?
 

There are many approaches to this..

Many lengthen the connecting rods.

You will want to ask the experts about the advisability of boring +.180", but, my Late Styled JD "B" has been +.180" since 1960 and is still going fine today..
 
You can safely bore to 4.6875 unless block is junk. I know people who have even gone 45 over that. Problem I ran into is the 4.6875 have bigger piston pins and orig rods would not work. Newer rods also will not work due to the journal being larger on newer tractors. I"d give josh blackburn a call he has helped us tons
 

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