One day I could hear, what sounded like, the rotor hitting the posts as it rotated. Put my hand on it. Sure feels like it is. He replaced the cap and rotor because the post contacts were looking arced real bad.

New rotor was scrubbing the inside of the top of the new cap. Thought that the rotor was pressed all the way down. Trimmed the top of the rotor to be sure it was not scrubbing the cap.

Still felt like the rotor was hitting the posts.

The distributor was the original out of the 305 (that the 350 replaced) so about 14 years old. Got a reman off of Ebay.
Same sound and feel.

Got an ACdelco cap and rotor. Same sound like the rotor was hitting the cap posts. It was not. Was adjusting the timing and noticed that if I tighten the hold down clamp some more, the noise got real bad.

Pulled off the hold down clamp. The distributor has some wiggle room where it goes through the intake manifold. It also appears to not set fully down, as in the shoulder does not rest on the manifold. Maybe a gasket or 2 or 3 gap.


Pulled the dist.
The wear pattern is on the very very bottom of the teeth.

I looked at the old one that came out. It's wear pattern is in the lower 20-40% of the gear. I did notice that the cross-pin that engages the oil pump shaft is more chisel shaped. The reman unit is more blunt. I'm guessing that it did not fit all the way into the pump shaft, thus the dist not setting all the way down.

I was going to swap back in the old dist, but it does not rotate very smooth as compared to the reman unit.
Any ideas ???

Distributor is the external coil type.

 

Anyone? This problem is keeping me from driving my baby.