Ive got a 4 bolt 350 that im going to rebuild over the winter. Im going to get it bored .030 over and get new pistons and all. Its just going to be very basic ~250hp. My question is, what do i have to do to the mains to run new bearings? Can i just put them in and torque the mains back down, or do i have to resurface the journals or mains? any help appreciated, or a link to something that would have this info! thanks

 

I am rebuilding a 350 4 bolt main engine right now. I had the journals of the crank polished and I purchased new main bearings from Summit Racing. I also, purchased the plastic gauge and measured the bearing to journal clearance. I strongly suggest that you do the same. You will need to get the rotating assembly balanced by a good engine machine shop.

If the jounals are in bad shape, then you should get them turned down to clean them up. Then you need to realize that you have to purchase the right bearings for the amount of material removed from the journals.

But if the journals look good, just get them polished.

 

Yeah the journals look fine, and it was a good running motor. So all i have to do is get them polished...ill have the same guy do it who is going to do my heads when i get the cash. Im just gathering parts and a rebuild kit at the moment.

 

Looking good isn't enough, they'll need to be measured.

 

The main bearings are never oversized. The caps are milled down slightly then the block is aligned honed back to exact size. The mains are always 2.100" on a chevy 350. The crank on the other hand can be under size the mains on the crank need to be measured to ensure they are 2.100" or extremely close. The block mains are measured with a dial bore gauge and micrometer.