Generation IV Internal Engine - 4.030 bore???how about 4.040 ls2

Hello guys and gals.

I just had my block bored, the machine shop was boring one of the cylindars and hit the cross link bar in the block and nicked the block so they had to bore it another .010 to make it .040. I've been told that .030 over in a ls2 is fine and there is nothing to worry about. I have some concerns with this extra .010 over. This now makes the bore 4.040, the guys at the shop said the extra ten is no big deal and it shouldn't hurt anything. I know some people are boring these engine to .060 over but they are not telling us that they also put block rock in them. I just wantted to know if going .040 over is going to be a big deal or not.

Wow...don't know the answer, but would be finding a different machine shop QUICK.

I think the machine shop should be buying you a new block.

so no one knows if it will be ok or not??? The guys at diamond said that the extra .0050 on the sides will not matter. Just trying to get your thoughts

Take a close look at each bore and determine if it is concentric with the stock sleeve. If they are all concentric then you will have no problem with .040" over bore. I have seen some LS2 blocks that have bad core shift and you can see it when examining it as mentioned above. You might try to measure the sleeve thinkness on the thin side and compare this with the thick side. A dial caliper and a magnafying lens with be helpful in this process.
Shirl Dickey

So how thin can it be before it becomes a problem on the thin side of the sleeve??

i would go get that machine shopt to buy you a new block and then get another reputable shop to do it right

So how thin can it be before it becomes a problem on the thin side of the sleeve??


We don't go under .100 on the sleeve thickness.