Flywheel woes

[grayhitandmiss]

I'm looking for a new replacement flywheel. The old one has a GM casting number 3988999N. The engine, I believe is a 1977 Chevy 350 cid. The flywheel is the 168 tooth, 14" diameter, with the 3.58" crankshaft bolt pattern. It's drilled for the 10.4" clutch.
This engine was out of a 1964 Chevy pickup I purchased, so the flywheel may not be out of a 1977 vehicle.
Is there a replacement available? I keep seeing GM parts number 3991469 while searching, but am confused as to whether on not it will work.
It states it's for clutch dia.: 10.4", 11"
Does this mean it's drilled for two different size pressure plates? I believe the bolt circle diameter for the pressure plate is 11-5/8" across.
Thanks for your help!

 

[grousehunter 61]

Somebody can correct me if I am wrong, but , if it is chevy it will work. I have put V8 where 6s were and used the same flywheel.

 

[BK72c10]

You need to have the correct weight fly wheel. Some engines like the BB 454 and SBC 400, 383 have external balanced issues. And you need the correct flywheel weight for engine balance. I would make sure you know your engine size and then get the flywheel. Call the Chevy parts department, they may be able to cross reference your fly wheel. And give you alternate part numbers.

Westfall GMC truck - KC, MO

These guys can help you out with your light duty truck, they have some old P/N books on hand and computers, if your local Chevy parts department cannot.

Sounds like the flywheel is drilled for both different sizes of pressure plates. If you can go with the bigger pressure plate and clutches. Get more power to the ground. But your bell housing ...etc may need to be for 10.4 or 11" only. Either way check it out.

 

[2tons of fun]

its a 350, there is no counter weight.

you can use the same flywheel from a 283,302,305,307,327,350.

just ask for a 77 truck flywheel and you will get the 11".

a 383/400 uses the same crank, h/balancer and fly/flex plate, it is externaly balanced and will not work.

a 396/402 bbc fly in not externaly balanced but it uses bigger bolts to teh crank.

a 454 is externaly balanced.