Thread: Distributor Arcing

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Hey guys, new here.

I have a 1980 camaro with a 350 that broke down on me the other day, when I finally got a chance to check it out I found this:







So I replaced the coil, started it up, and it was running really rough. The tach was all over the place and it kept misfiring. I started it again and walked up to the hood and heard a small buzzing sound that reminded me of electricity. I shut off the engine and took off the dust cover for the distributor coil, started it back up and sure enough it was arcing like mad. Mostly concentrated around the terminals, but some of it seemed to be coming from the 'coil tower' (I think I've heard it called).

My next attempt was giving the terminals a nice smattering of dielectric grease, but it didn't work. Then I cleaned all the contacts in the cap, which did nothing. I measured the resistance of the wires from the spark plug end to the contact inside the cap but everything seemed normal. So I replaced the cap and rotor. Which still didn't help. Next I replaced the ignition control module, which, surprise, didn't work.

I would very much appreciate any advice you can give me. Thanks for reading.

do you have the rubber ring under the coil?That cap looks rough maybe shorting out.

Yeah the ring is in there, I even rubbed dielectric grease all over both sides.

An old trick is to use a pencil eraser to clean it off but at best its just a patch.

Hmm, well the cap and rotor I bought came with a high resistance washer and a low resistance washer, but I have the high resistance washer in it. The instructions said the low resistance washer was for installing MSD ignition. I'll try to post a video up of the arcing later, in the meantime here's a thread bump with a picture of the car:

can you separate the 3 wires R,Y,B put some daylight between them. Try to keep the R&Y from touching the metal, slide a piece of electrical tape in there. Looks nasty, burned and un happy. See if that helps, I assume the arcing you speak of is happening there, dielectric grease is a conductor. Just somethings to check.

That picture I originally posted was the wires of the old coil, so when I replaced the coil along came with it new, clean wires, and I bent them so they're a maximum distance away from each other. Hmm I always thought dielectric grease was an insulating, non-conductive silicone grease. I'll try some electrical tape in there as well.

You are right it is non conductive was in the middle of an outage, in one of our gateways. Where is the arcing occurring that area in the photo or you just hearing it?

The arcing seems to be occurring between the terminals on the top side and the 'coil tower' or the rectangular part of the coil. It's kind of hard to tell but it seems to jump all over the place in that general region.

Bring your car into the garage turn off the lights and start it With hood open look to see where it is arching if no garage wait till night ...If you don't know where its arching you can't fix it.

Could the boots that are on each side of the terminal block be leaking, maybe damaged when things went south from before, you did clean them up? You mention a new dis cap so that's out. That black wire looks like it is ground and attached to the rectangular part of the coil. If I am looking at the picture the right way, makes sense a leaking wire would be flashing all around that area. As Charlie says run it in the dark to isolate.

Looks like those wires are shorting out against the metal piece that holds the coil pack down.
Isn't that setup supposed to have a cover over the coil on it? Also, doesent the coil cover also have an extended piece that covers the wires that would keep those wires seperate?

I don't mess with the HEI coils much.

I too was actually wondering if the cover would help reduce the amount it was arcing, but at one point it was so violent i have a feeling it would occur regardless.

While I wait for a night to go out and check the spark location (I don't have a garage) I may have stumbled across another lead (no pun intended, you'll see why in a second). There is a 3 wire connector that comes out of the distributor base and goes into the distributor cap. I assumed the black wire in the middle was ground, tested it with a multimeter to make sure, and it was indeed a ground. The problem is, where this connector attaches to the cap there is no contact for the middle ground wire, so there's a grounded wire coming out of the distributor base going to nothing. Should I be attaching this to the grounding strap to the coil somewhere? Maybe where the coil has a grounding strap to a mounting bolt?

ground strap.jpgYour missing the ground strap,it goes in the center terminal position on the cap and screws to the coil.

th.jpg Like this....