So this 90's 350 that im building up is gonna go to the machine shop to get bored. Since its getting done am I better off getting it .030 or .060 over? What cc head should I run to get the get a high 9 even 10 : 1 ratio? I blew up my truck motor this morning, pre 86 350 in that, so I have to put bearings and rings in that this weekend. Fun fun, hahaha.

 

.030 over. The extra displacement you get from an overbore is insignificant. A .030 over 350 works out to about a 355. A .060 over works out to a 360. 5 cubes isn't worth it. You're better off preserving the ability to bore that block one more time.

 

changing bearings and rings are just going to end in heartache unless you take that thing apart and clean out the metal shavings, or else it'll just happen again.

You dont bore a block for displacement. You bore it to make the cylinder perfectly round again to make the rings seal. Even at .060 over, you only get an extra 10 cubic inches. It's much easier to get a little bit bigger cam than to bore another .030 for 5 extra cubic inches.

You always want to take out as little metal as possible in order to preserve cylinder wall strength/thickness and leave room for future rebuilds. If you can get away with .010 over, do it.

 

its 2 different motors, but yeah, the one that i blew up im completely tearing down, its coming out friday night, the machine shop has a crank thats already .010 over and i have a kit coming tomorrow. The bored motor is gonna go in my 86 camaro. ill put pics on as soon as i can. its tore down right now, i just built a dash out of thin diamond plate that i bent and cut myself, i think it looks pretty sweet, even better once the guages and switches get put in. ill get pics on. i just figured since i was going to the machine shop i would drop the motor off at the same time and get put on the waiting list, which is why im buying a crank from them.