Harmonic Balancers

Rodger, I'm unfamiliar with the term "bench balancing". I assume the decision is whether to internally balance the motor or leave it externally balanced.

If so, I'm going to play devil's advocate and reverse your question. Ask your son what problem he is attempting to resolve by internally balancing the engine?

Doesn't the Cleveland work just fine as it came from Ford, externally balanced? I've never changed the balance on any Cleveland I've built. My opinion is that there should be a good reason based on solid mechanical principles for every thing you do when building a motor, or you are wasting time, money and effort. I've never built a motor that turns the type of RPM that requires internally balancing the reciprocating assembly. I always focus my effort on ring seal and valve train geometry & set up.

On the other hand, I highly recommend having the reciprocating assembly "dynamically balanced" as a last step before final assembly. I like the feel of a smooth running motor, and there is a practical reason for doing so, a motor that vibrates less is stressing its parts less as it spins & reciprocates.

Your "unbalanced" friend on the PIBB, 90 minutes away in Fillmore, George

Rodger,

Internally balancing a motor requires the use of an expensive heavy mallory metal. It is not cheap to do, and it isn't necessary for a street motor.

I very good idea, as George suggested, is to simply have the rotating assembly dynamically (externally) balanced. It costs $150 or so. What they do is make sure all the pistons and rods are the same exact weight. Then they bolt the balancer and flywheel to the crank and spin it (much like a tire being balanced). They then usually take away some weight where it's a bit heavy.

This type of balancing is always agood thing to do with any engine rebuild.

Michael