Skip to main content


chasing an electrical issue, which turned out to be a missing C-clip on the vacuum advance arm, I noticed the terminals on the distributor cap are exhibiting an uncommon arcing/melted plastic.

Any thoughts on the cause?

could the rotor somehow be sitting too high?

Duraspark with MSD6 and big blue MSD coil




Images (1)
  • 2023DED4-4D51-42EB-84C0-8BA15F60F269
Original Post

Replies sorted oldest to newest

1) you need the correct rotor and cap 2) the rotor must be fully seated 3) the cap needs to be seated correctly and both clamps attached securely.

The wear pattern on the inside of the cap indicates one of these issues. The clearances in there are actually quite close.

I'd speculate that it is a rotor problem. Replace both the cap and the rotor with a matched set.

If the situation repeats itself afterwards look for an issue with the distributor points cam. Verify that the horseshoe clip under the felt pad is installed correctly. If the points cam is not retained in place it will ride up causing your issue also.

Add Reply

Link copied to your clipboard.