95maroz28

iTrader: (21)

will i be okay using a .060 overbore block? I have a 4 bolt block ready to be assembled but had to be done .060 over. Most of the searches say .060 is too much for an lt1 block but ive seen a few stock eliminator guys using them. Its for an N/A motor.

SS RRR

iTrader: (2)

It's the most you should ever go. You should have your builder sonic check the cylinder walls before doing so.

joelster

Any LT1 block can be bored .060" over, but not many should ever be taken this far. The competent machine shops will measure the walls before they do this though. It may look fine to the naked eye, but there is a good chance it will be too thin to fully support itslef properly. I've always heard that .040" is a safe bet. I know it's a c-hair difference, but that's what i've always heard.

96capricemgr

iTrader: (1)

Depends how far you are pushing it and if it was sonic tested.

Ed Wright posted within the last week about how his NA 383 is pushing the bores around with a .030 bore. That is making 100rwhp more than most will ever make NA so it does not mean you have to worry.

Personally if the block needed to go that far I would have part filled it, but that has to be done before not only the bores are done but even before the main hone. The whole block flexes more than you would imagine.

95maroz28

iTrader: (21)

Not sure if it was sonic checked or not but its a good local machine shop. Id rather not have to worry about it though. Maybe id be better off just having the original motor bored .030 and with just arp main bolts. kinda sucks cause i already got the block ready to go.

edit* wouldve opted for the fill but its all been done

joelster

To be honest, there are a lot of "good" machine shops that simply think LT1's are exactly like older SBC's when that is simply not the case. Just go get the .060" block checked out.

engineermike

I'm at .060 over an 17 psi boost with no issues. Mine was sonic checked but not filled. I never expected it to live this long, but it has.

lifeisgood

iTrader: (4)

isnt a 396 60. over?

joelster

No.

An LT1 396 is a 4.030" bore (.030" over) combined with a 3.875" stroke.
A typical 383 is a 4.030" bore and a 3.75" stroke.

Chevym84

yea i wouldnt go 60 because yes its on the border of being safe and also u have a better chance of finding imperfections in the block. i say 40 is a safe bet..