I had a '63 Pontiac 389 where the pickup fell off, and coincidently at the same time some of the teeth on the plastic timing gear started to come off. One of the teeth got sucked up in the oil pump and jammed it up, breaking the oil pump drive shaft. The car quit running, and I worked on it for a week before I found out what had happened. Couldn't figure out why the distributor wasn't turning the pump.

I changed out the timing gear for a steel set, and obviously never had a problem again. I think Pontiac was using the plastic timing gears for a while to run quieter, or something, but in heavy duty use they were failing.


Don