Distributor caps

[RickC]

I had been having issues with #4 cylinder not firing. I took cap off distributor and saw that the plastic housing around one of the mount holes had what looked to be soot and a small horizontal groove in it as well as one of the brass lugs had a groove worn into it. Would this be the cause? It's one of those black replacement ones as well as the rotor. I cleaned up a used brown plastic set and installed it. Seems to be running ok but havn't road tested yet. Is there a source for quality caps?
Rick

[wesk]

That's called carbon tracking. The carbon is a byproduct of the arcing that occurs in there. As the carbon deposits build up they begin to conduct the spark away from it's intended target This results in miss firing, cross firing. You'll have to shop for US made caps and rotors.

[RickC]

Thanks Wes. This isn'r really tracking...theres actually a groove worn in plastic where it looks like rotor hit it. same thing on one of the brass lugs. I'm guessing something was out of round.

[wesk]

Then I would first inspect the distributor shaft for bearing play and straightness. If the shaft is true and has less than .002 radial free play then the cap and rotor have an alignment problem. Some of the cheap off shore caps and rotors can have this problem.

[G740]

I have NOS inner and out cap assemblies. Last contract of Prestolite before they closed the doors.
Midwest Military
John