Compression tested ok if 150 -180 is good. checked play in rotor again and noticed I could spin all the way around with a little force. Rotor is good and not cracked. Decided to remove points plate to look underneath. Things seemed to look good there. weights still in place. So is it possible the pin on gear on Dist. sheared?
Yes. This is actually a fairly common failure on 351c's.
The reason being, that car uses rubber"umbrellas" instead of positive sealing valve stem seals.
With age, they dry out, become fragile and crumble into the oil which gets returned to the oil pan.
Eventually the oil pump sucks up enough of them to freeze or bind up the drive gear while the engine is running.
The weakest link fails. Sometimes referred to as a fuseable link. That being the roll pins that hold the drive gear to the distributor shaft.
I've seen them just bent 90 degrees and not sheared. So probably the pump gear just bound up momentarily and cleared themselves enough. This will start a complaint about the engine "jumping timing".
The original oil pump drive shaft is a piece of hardened hex rod. I've seen thm twisted like a licorish stick so in that case it worked as a fuseable link and twisted before the pins sheared.
People who race will tell you that they have seen the oil pressure gauge readings bounce around under high engine load. That can be attributed to the hex shaft twisting and bouncing back.
Once you go to a machined "molly" drive shaft it will no longer flex and you had better verify the integrity of the drive pins.
The other thing which COULD have significance is that the outer ring ON THE HARMONIC BALANCER, IF NOT BONDED, with age has a nasty habit of rotating 90 degrees on the hub. That's just little enough to keep the engine running, but "just a little funny".
Here's the question that will point you in the right direction on the balancer. Have YOU had the balancer rebuilt?
