AMC 360 Flywheel vs 304 - Whats the diff??

JOHN360CJ5

What is the difference between the 304 and 360 flywheels? They both weigh 30lbs and have the same starter gear and bolt pattern.

dbesade

JOHN360CJ5 wrote
What is the difference between the 304 and 360 flywheels? They both weigh 30lbs and have the same starter gear and bolt pattern.

Balancing. You can't use a 304 flywheel/flexplate on a 360 (or vise versa) because the flywheel/flexplate is balanced per CID.

Go get a 360 flywheel/flexplate from the e-store or have the existing one rebalanced for a 360.

-Dave

tufcj

If you look at the back of a 360 flywheel, at the outer edge there's a cast in block, about 1" square and as deep as the flywheel, on a 304, it's not there. That little amount of weight and where it sits keeps the 360 from vibrating. I've seen guys get away with a 304 flywheel on a 360, I've also seen that combo vibrate so badly it cracked the bellhousing. As much work as it takes to change a flywheel, it's hardly worth the experiment if it goes wrong. Bob tufcj

JOHN360CJ5

Ah Ha ! Thanks for the info ! I built my 360 many years ago and had the whole engine balanced with the 304 flywheel that I had on hand. The 360 that I got used was off an auto trans, so I rebuilt it and used my old flywheel. It has always run smooth. Is there any benefit to replacing this now, as I replace my worn clutch disc ??

dbesade

JOHN360CJ5 wrote
had the whole engine balanced with the 304 flywheel that I had on hand.

If the flywheel has been balanced on a 360 then you should be good to go.

-Dave