Can I bore 0.060" over?

[adampecush]

Got the word back from the machine shop that my already 0.020" over block has some deep gouges in #6 thanks (likely) to the blown ringlands. Shop is going to see if it cleans up at 0.040", but if not, would have to go 0.060" over (84.5 mm piston). I know there are guys who are/were running big power on 0.060" over, and HKS made 0.100" over (85.5 mm) pistons, but am I asking for trouble?

Block is a <89 thin wall casting. If I can't find a better block local, what is the minimum cylinder wall thickness I can use (would obviously UT thickness check the walls before boring)?

Thanks,
Adam

 

[Another MkIII]

I was under the impression that .040" over is the max you cn go, but I'll let somebody who has more machineing experience verify that.

Also, do you have a link to those HKS pistons? I've never heard of anything that much oversize.
-AM3

 

[IJ.]

Seriously doubt an early block will go that big Adam, they could sonic check it before attempting it.

 

[Orion ZyGarian]

I havent heard of the .1" over HKS pistons before. I think this would be the ideal time to get an 89+ block.

 

[pogoism9]

Max bore on the block is 85.5mm, although I would be hesitant to bore that big on a 20+ year old piece of metal...

 

[adampecush]

assuming I do a thickness survey of the walls, what is the minimum thickness I can run?

thanks for the replies.

 

[IJ.]

Sorry don't have any minimum thickness data to share, it's a bit of a gamble at the best of times, back in my SBC days once you got to +60 you started having some weird overheating issues using the same non overheating hardware from before the bore job..

Even getting a heavy GTE block may be a gamble as I noticed my brand new block had a LOT more core shift compared to all of the early blocks I'd worked on..

 

[adampecush]

oh I'm certainly not set on .060 over, it was just out of necessity on this block. shop is going to bore #6 and see how it looks roughed up for .040 over. A member local to me threw out two gte blocks last week...had he not done this, I wouldn't even be making this thread.

Thanks again.