I have a '69 Chevelle with a mild '84 461, HEI, Edelbrock 650 AVS, and high rise intake. I use MSD wires.

I just changed the distributor cap that had about 8,000 miles on it. I noticed that tip of the rotor and the contacts inside the cap had dark burn marks. The burn marks inside the cap are black with white edges. They're about 2mm x 3mm tall and wide, and protrude about 0.25 - 0.5 mm. The black burn marks aren't in the middle of the contacts -- if you're looking into the distributor cap, they're on the right sides of the contacts, with white tails going to the left. Also, keeping the cap upside-down, the top 1/2" of the rim has a strip of fine, black particles.

This seems a little extreme for 8,000 miles of wear. What is it saying? Are the spark plugs too hot or cold? Is a wire faulty? Bad coil? Bad module?

Thanks for any insights.

Anybody have any idea why the burn marks are off center? I've seen heavy burn marks before, but they've always been in the middle of the contact.