How far can you bore a 360 safely?

[myasylum]

It has been noted that my 360 has already been bored .040 over. is .060 safe... I'm kind of worried, but you guys know more than I. It's a 10/12/71 block. I have seen pistons for .070 over, so I don't know?

When they checked the block it was a .045! Don't ask me? So they said that had to go to .060. They figured who ever bored it the first time at .040 did something screwy. You'd think it wouldn't run.

also at .060 over what would that make it in Cu in? and what difference in HP is that, if any?

Thanks!

(still searching for rings for the KB107's by the way!)

Thanks!

 

[rumblefish360]

To know for sure, you'll need to sonic check it. That is the only 100% sure way.
Just because you got it at .040 overbored dosen't mean the engine was bored before the last owner.
Even if the last owner was the first and only owner of the engine/car, the cylinder walls may have been creamed by a broken ring that just dug into the cylinder wall.

With a .060 overbore, you'll have a 370 cubic inch engine. The HP difference will be extremely small. In searching for HP, the overbore is probably the smallest gain in power unless the cam is smaller or the compresion ratio drops and the rest is stock.

 

[fishy68]

Rumble's right. Sonic test it before you bore it .060 over. I have an early 360 block. You know the one that's supposed to be a thick wall block as alot of people claim. Well it does weigh 4 lbs. more than a 79 block I have setting here so there is some more material somewhere. Well I had it sonic tested and found one side was plenty thick enough on the major thrust side of the cylinders to be bored .060 but the other side would have been pushing it to the limit. This was due to some core shift which made one side of the block's major thrust side better and the other worse. If my old "heavy" wall block wasn't even safe going .060 over not many others are I bet.

 

[Demon416]

.060 over is pushing it. Sonic test it before you bore it .060 over.