EvilCartman

iTrader: (1)

What are the drawbacks or problems of boring .060 over instead of the standard .030 over? I don't care about getting another rebuild out of the block, 350 blocks are a dime a dozen. Will there be an issue with running hot? I'll be using a griffen radiator and be putting out around 475 hp. Possibly a 250 shot later on down the road.

ede

yeah, warpage from excessive heat caused by the walls being to thin. i'd use sleeves if i had a block i needed to save before going .060 or have it sonic checked before going oversize.

ctandc

I have to disagree on a 350 block...ALTHOUGH it depends alot on the particular casting. What's the casting # of the block? I've seen countless '010' blocks bored .060 over with no problems.


Circle Track racers do this ALL the time. The only downside can be piston selection in that oversize.

To be honest, I'd just leave the decision up to your machine shop...you do trust them right? As a good machinist will let you know. Also make sure they are boring using a torque plate, as most everybody should by now.

Sonic checking could be done, but to be honest, the cost / labor of this usually is worth more than the cost of another block.


Just my 2 cents.

heavy_chevy29

more of a chance for cracking during the boring process(do to core shifting). but them again the block can crack if you go .030 over. if your not worried about geting another rebuild out of it then i would say go ahead and do the .060 over bore, good luck.

Air_Adam

.060 is the bore limit. I was reading a book of my dad's about the history of the SBC and how to hodrod a SBC (was made in '72, newer blocks may be different)

Anyway, it was saying that its really not a good idea to go more than .040" over, because when you get to .060" over, the cylinder walls get very thin, so the block will probably not last very long.

dans82bird

wow, i didn't know they put sleeves in sbc's... i remember when i had my kx125 we had the cylinder re-sleeved when we rebuilt it... how do they hold up to a high performance motor?

Guest

From .030 (if its already there, or .030 isnt enough to get good shaped cylinders) you should try .040 first. On a daily driver/street type engine, you shouldnt ever bore it out to make more power.. leave that to the racers. Not sure if thats what your idea was or not.

D Stroy H8

I think he just wants a good rebuild. Just let the shop judge it. A .04 overbore will probably do the job. 0.60 would be unecessary and too extreme IMO. Oh, and if you are thinking in terms of more power from .04 to .06... very marginal.

EvilCartman

iTrader: (1)

I was kinda going for the max power out of the thing hehe... Think I'll stick with .030 over after what's been said here. The block in question is an 87 350 out of a truck that is all stock. (not for much longer though ) The machine shop I'm going to use builds high performance engines plus regular stock rebuilds. Haven't talked to the guy yet but I've seen 3 of the engines he's done and they're damn good. Thanks for all the input