[Jay S]

I follow now….RBailey, The harmonic balancer was bad on that engine. There is more to it than it fitting tight on the crank snout. The inertia ring can look like it is in good shape, and feel tight, but the rubber connecting the hub and inertia ring can get old and let the inertia ring on the outside move just enough that it is bad, making the harmonics on the crankshaft worse. It broke in the exact place I was asking about. Breaking on the rod throw in front on the number 2 main seems to be from a bad STOCK balancer.

We had an engine that no matter what we did we could not keep the belts on in. Everything was perfect on belt alignment. We eventually figured out the harmonic balancer was bad, replaced it, then it was fine. Belts lasted forever after that. There was nothing at all that indicated the balancer was bad on that engine. If your lucky you will have the timing marks shift to indicate it is going bad. Many occasion’s though, it can be bad and the timing marks still line up. Having the belt whip excessively when you rev the engine up can be a sign the harmonic balancer isn’t doing it’s job, so is having issues with the crank pulley’s breaking.