Distributor cap - Lost power found?

[Walt Fricke]

At my second race this year, my second practice time in the 1 minute 42s dropped to to 43s, then 44s then 45s each successive session/race. WTF. It wasn't tires.

I checked leakdowns, compression, cleaned plugs, checked timing, adjusted AFR, and basically wasted time checking valve lash.

Just before my last race I happened to notice that the "lead pencil" graphite or whatnot little cylinder inside which connects the spark coil to the rotor in the distributor cap had broken, and the brown plastic (Bakelite?) around where the pencil emerges had roughened and was a lighter color, making a nice small circle visually.

My theory is that maybe I hadn't pushed the rotor on firmly enough, so it sat too high, and this caused rubbing and stress and it broke up inside.

And secondarily, having to jump this new gap cost me some power.

Might I be right about either of these guesses?

The cap wasn't that old.

[Jeff Alton]

Walt, Check to see the trace lines on the new cap vs this one. If they are different, then yes, the rotor may not have been seated all the way down.

Cheers

[Walt Fricke]

Are there trace lines here? What and where would they be? Actually, I was using a Dremel to clean up the copper contacts when I saw that the center bit was missing. Not very observant. Before taking the picture I wiped the miscellaneous dust away.

I'll take a look at the replacement (not new) cap, though.