Burnt out Distributor Rotor

[lugbutz]

Hi
I was working on the car, replacing ignition cables and checked out the distributor when I noticed a couple of things.

1. The Distributor cap had a huge chunk out one side where the number 1 ignition cable should go. It looks like this
https://drive.google.com/open?id=1zYqi3 ... sp=sharing

Inside the Distributor cap looks like this
https://drive.google.com/file/d/1DrFq2s ... sp=sharing

2. The Rotor its self looks like this... To me it seems that there was a short or something
https://drive.google.com/file/d/1dv8Z-P ... sp=sharing


My question is why did this happen and can I prevent it in the future?

[MattVAS]

Looks to me more like the rotor hit one of the hanging probes for the cables.
This can happen for lots of reasons. But if you have not done anything to your system and this suddenly occurred then the issue is the distributor bearings. This can cause your shaft to wobble and then that can cause a collision.

[DieselSpider]

Yep worn bearings in the distributor, rotor was not on tight or a screw came loose and was flying around in there.

Was the rotor on loose or one of its screws missing or a screw missing on the points, condenser, etc? Does the shaft wobble side to side?

[wetminkey]

Be sure your rotor screws are tight!

[DieselSpider]

Snapped the shaft on that one Minkey.

Reminds me that one of the springs on the advance weights could have come flying off too.

[wetminkey]

Naw, man, you're thinking of other distributors,...
For '79, the plastic rotor just screws down onto the advance spring plate (and settles into those small holes,...one square, one round,....for proper orientation.
Just blew apart the rotor, cap, and bent one of the screws that hold down the rotor. Could have got it running on the spot, if I'd had a new rotor, cap, and a screw!
Wife towed me home, and then came the long wait for parts to come through the mail,...

[spider2081]

Just blew apart the rotor, cap, and bent one of the screws that hold down the rotor

I think the rotor screw threads and tension washers are reaching the end of their lifespan. I like replacing the rotor screws with new ones having a philips head and installing new star washers with the new screws.
I also think either the new rotors or distributor caps are slightly out of spec. On more than one occasion I have replaced the rotor and cap on 2L engines and found the rotor is striking the #4 cylinder post in the cap. The original caps had no evidence of rotor/cap interference. They were old and corroded.

[RRoller123]

+1, A long time back, I had a rotor that was made improperly, with an eccentric in it, and it struck the cap at one particular spot.