Dan_Thomas_ wrote

Sometimes. Many of them aren't heavy on one side.

I'm not surprised. The engines I am most familiar with are weighted, but I
don't have much exposure to a lot of engines. I should have used another
weasel word like "some of."

The "harmonic" part comes from the fact that it's two pieces of metal, an
inner hub and outer ring, with rubber between them.

Right, which is why I said "part of the function."
--
Jim in NC