I've removed the 454 Gen IV motor from my formula and am replacing with a rebuilt Gen V motor. the question is can I use the flywheel and coupler from the gen IV on the Gen V.
the old motor was a 1990, the new is 92-96 vintage. or so i'm told.

Thanks

The IV's and V's have a different balance and the V's have two different flywheels, one forged and one for cast cranks. Any good machine shop can balance your Mark IV flywheel to Gen V specs for about $50. Good luck.

So basically as long as the flywheel fits the crank properly I just need to get it rebalanced?

Just use the Gen V Flywheel .... the coulpers are the same ...

Yes, all big blocks and old small blocks have the same crank bolt pattern. Just make sure you get it balanced to the right specs, or like offthefront says use a Gen V/VI, just make sure it's the right one. The cast cranks have a different balance then the forged..

On the Gen V, the harmonic balancer and the flywheel are different then the mark 4.

You can use an automotive flywheel with a new style coupler and a new style bell housing.

If you use the old style coupler, you will need to use the old style bell housing..

I just finished a motor swap to a Gen 5 from Mk 4 this weekend..

In addition the sea water pumps are different on the Gen V if you want to use a mechanical fuel pump for a carb. Or, you can use an electric fuel pump if you are using a carb or EFI.

In addition, the oiling system is different on a Gen 5..

If you close the cooler lines along the pan rail, you need to be sure the bypass valves are redone accordingly.. If it's a Gen 5 marine motor, then you should be able to bolt in the oil and cooler lines in the filter adapter...

I chose to use the cooling lines in the pan rails, and not use the Merc Filter/Cooler adapter.... (Less plumbing hoses and more space). In addition, I am using an electric fuel pump...

Hope that helps.....