Boring

[Billt]

I am building a new motor and one cylinder took .040 to clean up. There was water in one cylinder when this block was in the junk yard. It did not completely clean up . There was a pit where the top ring was and that cleaned up nice, but there are still some small spots that are discolored. It looks like it is just stained and you can not feel anything with your finger nail. It looks almost like you sprinkeled a little pepper in there. We have not honed it yet so we will take another .001-002 when we fit the pistons.

My choices are:
1. leave it alone
2. Bore to .060
3. Sleave it and bore to .040

The application is in a boat and it will not run over 3400 RPM. I plan on using speed pro moly rings.

[302man]

I would go sonic check the walls and see how much you can go before you take any chances.

Most blocks can't go .060 over. Walls are too thin. Most 302/351's don't go over .040 . If you bore one cylinder to .040, you need to do them all at .040 over. You don't want to have an out of balance rotating assembly.

[Kevin Price]

Yes, I'd have it checked. I just recently disassembled my wifes race car to find it is .60 over. I honed it and put it back together but I wouldn't recommend going out that much.

[sn95gt19]

i keep hearing that its unsafe to bore it more than .040 over...but we just pulled my buddies motor out and brought his block into get machined .030 over....turns out the motor was a warranty replacement from ford, and it was already bored out .060 over.
i thought it was kinda weird for ford to do that to a replacement motor

sorry im a little off topic here

[Billt]

The machinest said the little marks I see are OK, and when he hones it more of them will clean up. I took the edge of a rasor blade and can not feel dips, so I know they are not deep. Are a few tiny spots OK or will this kill the rings faster than normal.

My choices are:
Bore it to .060
Build it like it is
I have not asked yet, but I think you can sleave it
Buy the other block at the Junkyard and start over

[sn95gt19]

Originally posted by Billt
The machinest said the little marks I see are OK, and when he hones it more of them will clean up. I took the edge of a rasor blade and can not feel dips, so I know they are not deep. Are a few tiny spots OK or will this kill the rings faster than normal.

My choices are:
Bore it to .060
Build it like it is
I have not asked yet, but I think you can sleave it
Buy the other block at the Junkyard and start over

i personally would buy a new block from somewhere (summit has them for a little over $300) and start over.
its not very safe to bore a stock block .060 over

sleaving it is probably going to cost more than buying a new block and starting over.