big vibration with new 351w

Hello

I have bough a rebuilt long block to rick malaga in florida, on ebay, it's a 351w marine from 1992

the engine have to go in my boat, a correct craft 1992 ski nautique

the problem start when the engine start for the first time, it was chaking a lot, vibrating..

So I call the guy and he told me I must use a internal damper and flywheel, so, I bough on summit a new internal damper, and rebalanced the original flywheel to zero as he told me, vibration was More dramatic!

Now he told me it's my fault because I didn't use the original parts...and aftermarket won't work on those engines...

there is a 50oz flywheel possibility? is that true, how can I be sure it gonna work?


thanks for helping me

Peter

Here is the skinny

Small block reciprocating assemblies have some balance. The compact lightweight crankshaft itself does not carry enough counterweights to achieve zero balance. Extra counterweighting is cast into the flywheel and harmonic balancer bring the entire assembly into neutral balance. Early engines use 28.2 oz.-in. external balance, while 1982 and later engines use 50 oz.-in. flywheel and 34 oz.-in. damper external balance. All 351W engines use the early style 28.2 oz.-in. external balance.

Unless PCM was screwing with you your engine and damper/flywheel combo should all be 28in oz. If it is an exotic shortblock setup with a stroker crank or with added heavy metal to allow for an zero internal balance then you would need Zero external Balance but that wouldnt ensure that both the flywheel and damper had to be zero just that together they were zero. Might be you need to get a zero balance aftermarket flex plate and have the balance of your flywheel changed to match it. But I think you should talk to the builder and let him know that we can have a ccfan reunion at his door step if he cant make this right.

Ditto Joe on what the Dude says...I don't know what you're sayin' but I sure like the way you say it.

john