THRILLSEEKER

How far can you go on a 350cid block without making any major alterations......like filling in cooling cavities?

Cord

I thought that it was .060

Vinny P

It really depends on the block. Early LT-1 blocks will go to MAXIMUM of 4.060 , but I would be leary about punching a late model stock Mercruiser block .060. I would feel save at .030 or max .040. But the problem is if you have to go .040, pistons get expensive and hard to find.

traviss

I only go .030". if the motor breaks and cause's damage you still have cleanup room bore .010" to make .040" over. and still have substantional wall thickness. Cause if you go .060" and have a uncentered cylinder your cylinder walls could get thin. You could have it checked with a sonic tester and see what kinda wall thinkness's you have. If your running a stroker with short rods it puts alot more pressure on the outer side of the cylinder then normal and it will probably crack the cylinders at .060". Its up to you bro.


Travis

THRILLSEEKER

Well I am no machinist but the guy at the machine shop who is doing my work said that the block was already .030 over and it was either .006 or .016 out of round and they were going to have to take it to .060 does this sound right?

There was a lot of background noise so I may have misunderstood him.

Iggy

I believe the next step would be .060 over.
Pistons come in .030, .040 and .060 steps in bore size.
Remember, when they bore it out .030 it's only .015 off each side of the bore (.015+.015=.030). So, if it is .016 out of round and if he was to go up to .040, that's only a .010 increase (.005 per side), it won't be enough to straighten it out. He would have to go up to .060 to clean it up.
Double check with the machinist to be sure of what he's going to do. Maybe it would be more cost effective to buy a short block assembly.

THRILLSEEKER

will it hurt the engine if I build it back the same it was (except for pistons and rings).....same crank, cam, heads, intake, carb....bla...bla...bla? Also how will it effect my twin engine application if both motors are built exactly the same except for one having a .030 bigger bore size?

blown1500

One engine .030" overbored will make no noticable difference in the engines. TRAVIS'S advise about the sonic check is good, small blocks could have problems anything over .030", but some can take a lot more. Sonic is the only way to know.

Vinny P

I am not an avid believer in sonic testing. Maybe I am wrong here, but from what I see, a sonic test only checks the cylinders in a few spots. It can't test the entire cylinder. What if it misses the thin spots???

blown1500

Sonic checking does not check the entire cylinder, just the spots they test. You could have a thin spot and not detect it this way, however, most cylinders are thin in specific areas, core shift is readily determined, and most operators know the places to check for best success.