Distributor cap arcing

[radi8u]

Festy started running rough, thought it may be fuel related but pressure checked out within specs. New disty cap and rotor, spark plugs were next. Arcing from cap to body of disty now. Plug wires next?? They are Napa Premiums and are 2 years old. I remember something about the gasket that goes under the plastic piece behind the rotor, mine is pretty well shot, could that be the issue?? And does anyone know of a source for said gasket? Any and all advice will be much appreciated!!! Thanks!

[FestYboy]

The cap is an insulator, so if it's arcing from the cap, there's a carbon track that's allowing the spark to skip the wire post and complete the circuit at the dizzy body. Look for cracks and or unusual lines in the body of the cap.

[radi8u]

Thanks for the help, Festy. Odd thing today, went to the JY and got another distributor. On the way home it cured itself....

[Greywolf]

Condensation/Water Intrusion is another cause - especially with a distributor mounted horizontally. Water can pool in the bottom side of the cap and raise all kinds of cain. The solution is to put a bead of blue silicon around the mounting groove of the cap to seal it, but a drip channel should be left on the very bottom so that any trapped water can run out.

If you look at most light assemblies you'll notice a drain hole in the bottom, and that's why.


Another cause can be bad seals in the distributor shaft - allowing oil or oil vapor to get inside the distributor cap

[radi8u]

Still haven't figured this thing out. It'll run like crap, spittin' and sputtering, shut it off and fire it back up and it doesn't miss a lick. When it's cold, it misses but if I let it warm up it comes out of it. I've put another distributor on it with the same results. I tried to pull the codes by grounding the STI wire but the CHECK light never did go out when I turned the key on. Is that normal? According to Haynes it should go out. Even though the fuel pressure checked out okay, I may put a pump and filter in it to see if that cures it. Any thoughts on this???