Question about balancing rotating assembly

yellow rose said

Yep. Seen it myself. I’ve been told chrysler used what is called mass balancing. I’ve asked some of the smartest people in the industry to explain it, but no one could.

You can be pretty far off with the counterweights being heavy and it won’t hurt most Street/strip duty stuff. When the counterweights get light...hang on as they shake like a dog pooping peach seeds.

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I had no idea that a dog pooping peach seeds would shake :)

All that being said, I was primarily concerned because I don't know the history of the engine, and although the rod casting numbers were all the same, I can't say for absolutely certain that someone didn't swap rods from another engine and they weren't originally closer in weights. While I can weigh rods and pistons and rings, cranks are a little harder. And I'm told trying to spin balance it with an air wrench is a bad idea :)