If I know the necessary bobweight can this also be applied to an externally balanced engine?

In other words, I can send an internally balanced crank off to be balanced just telling the machine shop the bobweight, but with an externally balanced crankshaft can I do this also or is it necessary to include the damper, flexplate, piston assembly?

 

They should be able to do it. Call your shop and ask.

 

Thanks. What's "better" internal or external balance? I'd assume internal, but is the difference worth the extra cost?

 

External is fine. Internal might be "better", but can require heavy metal in the counterweights sometimes, or longer rods and short pistons to clear the counterwights, and other expensive details.

 

Depends on how accurate you want the balance job. My rotating assembly is currently at the balance shop. There's more to balancing than just knowing the bob weight. The balance shop will get the total weight of the rods, rod bolts, pistons, pins, rings, rod bearings and pin locks if they're floating pistons.

If the pins are not all the same weight, any even in a matched set can be a few grams off, the pistons are matched to the pins to get an equal weight. The rods are then weighed on the big and small end. They can all have the same total weight but if more weight is on one side than the other then they're not the same and not balanced.

For an externally balanced crank, they need the dampener and flexplate to spin the crank up since the counterweights on them become part of the crank balance and are not considered bob weights.

The balance shop I use also wants the neutrally balanced dampener and flexplate to make sure that everything is balanced.