Engine overhaul JD Model D

Tnbshr

Member
Good afternoon,
Im boring out the cylinders on my D tractor and im having to go to the .250 oversize and im worried about the cylinder wall thickness that will be left. Does anyone know what the minimum thickness should be?
 

Go with 45,90 or 125 over instead ?
Gasoline compression ?
Getting the cam and followers re-ground to compensate for wear . The duration can also be tweaked to make the engine run better.
Cold gasoline manifold with dual stacks ?
 
(quoted from post at 12:25:52 08/15/20)
Go with 45,90 or 125 over instead ?
Gasoline compression ?
Getting the cam and followers re-ground to compensate for wear . The duration can also be tweaked to make the engine run better.
Cold gasoline manifold with dual stacks ?

At ,125 there was still pitting so they had to go .250, gas compression, single stack
 
Tnbshr, and where do you find pistons that big? i would think a replacement block would be the cheaper option than boring that big and finding pistons, unless you already have them.
 

Pits are not a big deal. If properly honed you won't be able to catch a fingernail on them.plus it is not being used a in Cessna 207 .
The dual stack uses a cold intake that works better with gasoline.
Gas or all fuel compression ratio ?
 
In my experience it is best to get the pistons in hand before proceeding with boring. It's no fun to have a block bored and discover no pistons available. My friend ran a machine shop and he got so he would not bore a block without actually micing the pistons. It turns out not every piston specification is correct and not everybody is a skilled mic operator.
 

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