My 355 is 90% done. I am getting ready to put it in the car, but I have one important question. Which flywheel/flexplate should I use? The block is:

1980
crate engine
2 piece seal
4 bolt mains

I am hooking up to a 1983 700R4. Will the 1983 LG4 flex plate off my old engine work?

Thanks

 

Yep.

 

Are you 100% sure? I am so confused, I have heard a million different stories... about how you need the right one to keep it externally ballanced. Thanks for your help!

 

A 1980 2-piece rear main crank has the balance cast (or forged) into it on the output flange, and is "internally" balanced. The '86-later 1-piece rear main cranks didn't have that counterbalance on their round flange, so the weight had to be added to the flexplate making it "externally" balanced.

Your '83 engine had a 2-piece, internally balanced crank and no extra weight on the flexplate. Therefore, it will work just fine on your 1980 engine.

So much for the short answer, but that's a 100% sure answer IF the info you provided is correct.

Or, to put it a different way, if your '83 flexplate will bolt up to the crank on your crate engine, it is the right one.

 

Thanks guys, I think I'm ready to drop this beast in the car!