how much can you bore a 4.1

gobabygo

Member
does anyone know roughly how much you can bore a stock gm 4.1 block? like what bore size will it be? roughly. thanks
 
Iirc the bore on these motors are 3.965 I would only bore it enough to clean it up to keep the block as strong as possible since they are not know to be the strongest in the first place.
The most I have heard of is 55 over which would have a bore size of 4.02
 

dlafont

Senior Member
Iirc the bore on these motors are 3.965 I would only bore it enough to clean it up to keep the block as strong as possible since they are not know to be the strongest in the first place.
The most I have heard of is 55 over which would have a bore size of 4.02

They can be bored without trouble around 0.035 over to 4.000". I've heard of going a little farther however past that you will need to get a sonic check to make sure the cylinders are not shifted too much and there is room left to work with.

D
 
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