here is what i want to do.i am going to build a 383 with a 1 pc seal block.then run a t56 trans behind that.here r my questions:
1) should i get an internaly balanced kit or externaly balanced,which is better?
2)can i use the stock t56 fywheel?
3)is the stock 1pc seal block internaly or externaly balanced?
4)which balancer do i need 400 or a 350?

 

The 350 is internally balanced. If you get an internally balanced 383 kit you can run a 350 balancer and a stock LT1 flywheel and you'll be fine.

 

thanks but someone just told me today that the 1 pc seal motors r externaly balanced.which one is true?so you are saying that i will be able to use my stock flywheel and a 350 balancer if i go with the internal balace kit?

 

What J said is correct, and a 1 piece rear main seal motor is internally balanced, the 350 anyway, which is what you'll be using to go 383 I assume. Good luck! What kind of car is it all going in?

-Rippin

 

All SBC's are internally balanced except the 400. The 1-piece RMS engines use a small counterweight on the flywheel to accomodate the newer seal design, but the crank throws still have counterweights and it's still an internally balanced engine.