just installed a 454 in my 69 chevelle. All internally balanced by a large race engine shop in Mpls. Put on a new flywheel and new hi perf clutch. Flywheel was supposed to be balanced also. I have a bad vibration over 2500 rpm that gets worse as rpm increases. My mechanic says we got a bad flywheel. Any thoughts?

Maybe the autoshop had the flywheel internal balanced,and the 454 crankshaft still balanced for external weights?

yeah my first guess would be to check if you have a counterweighted balancer and flywheel

mike

If the 454 is internally balanced, then you need to run a non-counterweighted flywheel and damper, like the ones off a 396/402/427 for instance. That's the point of internally balancing a 454, so you don't need the counterweighted parts. This deal is completely unnecessary for any reasonable street engine.

Tom

I had a water pump bearing go bad in my 454 once, causing a bad vibration. Check it first, MAYBE you'll get lucky and not have to tear down the engine.

jrm,
Are you sure the motor was "internally" balanced ?? This is not a normal operation except for all out race motors. A good indication would be the amount you paid for the balancing. It should be in the $400 to $500 vicinity for an internal balance job on a 454 with "heavy" metal. Call the shop that did the balancing and ask them to find out for sure.
Also, as tombob mentioned, if the motor was indeed internally balanced, you need to run a "neutral" balance flywheel such as for the 396 and 427. Same goes for the harmaonic damper.
Hope this helps, let us know what you find out from the balance shop.


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Bill Koustenis
Advanced Automotive Machine
Waldorf Md

i was under the impression that if they balanced your 400sb/454bb rotating assembly with the damper & flywheel that it would still be considered internally balanced

Mike,
Just the opposite, when you internally balance a 454, or a 400, you no longer have to use the weighted balancer and flywheel, therefore, they can be left off when balancing the crank. You just balance them seperately to a "neutral" or "0" balance. The whole idea of internally balancing a crank is to add weight to the counterweights with "heavy" metal slugs in order to eliminate the weight on the flywheel and balancer. Having the weight inboard of the front and rear main bearings, instead of hanging outside on the flywheel and balancer, is much easier on the bearings, especially on a high rpm motor. The reason GM (and others) use the external method of balancing is because they cannot make the counterweights on the crank large enough to counteract the piston and rod weight on the bigger motors. You can do it on the 427's and 350's etc, because of the shorter stroke, gives more room between the bottom of the piston and the crank.
Some balance shops will put the balancer and flywheel on the crank of an internally balanced motor AFTER they get the crank balanced, and use the crank as a means to spin the balancer and flywheel to balance those individually. I prefer to do them seperately on a flywheel arbor. That way There is no interaction and you can replace the flywheel without having to rebalance the entire assembly. If you have any other questions, feel free !


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Bill Koustenis
Advanced Automotive Machine
Waldorf Md