John Deere 40 block question

[golfcartman]

What is the max that a John Deere 40 block can be bores safely?

 

[M-MAN]

I would search around and see what size pistons are available. You can always have sleeves put in and go back to standard.

 

[buickanddeere]

Free online parts book at the JD website shows 20 thou and 40 thou oversize pistons and rings

 

[Hay maker2]

(quoted from post at 12:26:56 09/13/21) What is the max that a John Deere 40 block can be bores safely?

I put 0.125" oversized pistons in my MT almost 20 years ago.

 

[buickanddeere]

Wonder if anyone has tried 4.25" bore 420 pistons in a 4.00" bore 40 ? That would make the cylinder walls 125 thou thou or 1/8 of an inch thinner . Don't know if there is enough metal in the block bores or not ? I'll bet a six pack of beer that those old blocks were cast extra thick and would take a 4.25" bore .
If you hit water at 4.25" over bore . Then sleeve the bores back to factory standard 4.0" bore .

This post was edited by buickanddeere on 09/14/2021 at 11:39 am.

 

[CPeter]

.125" used to be around years ago. I remember looking for some. I did not go through and actually buy them, but I was looking at having an already oversized block bored and found then available.
Peter

 

[bbplayer5467]

I would search around and see what size pistons are available. You can always have sleeves put in and go back to standard.

Do you have the website to buy those sleeves? For some reason I cannot find them

 

[Jim.ME]

Those are not sleeved blocks, a shop has to bore them to fit a sleeve. Best to discuss with a shop and get pricing for them to bore the block to fit sleeves they get, and for them to install and finish to size those sleeves. Don't put yourself in the mix for that operation. bearings and such are becoming harder to get for those engines. Be sure you have a source for those before spending a bunch of money on the block.