I was asked a question today about the engine I'm building. I was asked is it internally or externally balanced. Well all I got was a stock block and heads. No flywheel or harmonic balancer. I've asked several motor guys locally but not marine motor heads. The crank is drilled out in places, but I was told that MPI motors are externally balanced. This is definately a stock 330 HP/454 block and heads. I got some guidence from Shooter who said he's never seen an internally balanced MPI motor. Then I read a couple articles on OSO that say all Gen V/VI are internally balanced. Please help me figure this out. Thanks in advance for any help you can provide.

all 454 and 502 engines come externally balanced.

If it is a stock GM crank, then it CAME externally balanced.
If it's been internally balanced, you'll find a LOT of weight added to it on the throws.

MC

Should be external balance.

That is normal, it is from when the crankshaft was balanced at the factory. All of them will have some holes drilled in them.

Hope this helps,

Bill Koustenis
Advanced Automotive Machine
Waldorf Md

Thanks guys for the quick reply. You've been alot of help. Thanks again....

Make sure you get the right flywheel and balancer for the Gen motor you have. All 3 generations are all a little different. When you get your parts spent the extra couple bucks and have everything balanced. Last do not use one of the liquid filled balancers. Boats sit to long between starts and the liquid pools in the bottom of the balancer and has been known to snap the snout of the crank on cold starts.