Mike---You were fortunate that the flywheel didn't completely let go,
with just two bolts (and locating pin?) holding it. Old race cars were
supposed to have "scatter shields" in place to protect the driver,
should this occur. Anyway, it sounds like the engine was capable of
reaching an rpm where harmonic vibration would take place at the crank,
which is somewhere between 6200 and 6300. I will recommend that since
you will probably be taking out the crankshaft to replace it, or clean
up the damage at the snout, that would be a good time to add two or four
more bolts. I did this years ago, mostly as a precaution, since this
engine was also capable of shaking the flywheel off. Not having room for
hex heads, I used eight, socket head, aircraft, cap screws.
Dick
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