Coil Arcing from Ground Post to Center?

[Duffman]

Never had this issue before, but started my car to adjust the carbs and noticed a few intermittent arcing sparks on my coil from the ground (negative) post to the center wire from the distributor through the plastic housing. Happened just a few times and then stopped. Weird! Have not done anything new to my electrical recently. Have Blaster coil, e12-80 electronic ignition, and recently new, thicker spark plug wires. Car stumbled slightly when the arcing occured. Any thoughts?

Edited April 25, 2012 by duffman

[SteveJ]

Not enough insulation. How old are the wires? Could the center wire be nicked somewhere?

[Zed Head]

Not good. Your E12-80 module won't like those voltage spikes since it's on the end of the negative post circuit. You're blasting a lot more voltage through there than it was designed for.

How close is the coil negative post to the distributor cap and/or its center wire? That might be the source of the problem. Sounds like it's too close. The spark you're seeing happens when the module grounds the coil negative. So it makes sense that the coil negative post would be a good path to ground. Easier to go there than jumping two gaps. Could also be that your center wire isn't seated completely. That would be three gaps.

[Duffman]

Will take some pics and show the setup. Spark plug wires are almost brand new, heavier gauge than prior wires.

[Zed Head]

Hey, I mis-wrote above. The coil sparks when the ground to the negative post is broken, not made. So the spark jumping to the negative post shouldn't happen unless you have a short in that wire or it's jumping to ground farther down the line. Maybe you have a pinched wire in the distributor.

[beermanpete]

It might be arcing down to the ground due to dirt on the coil. Remove the high tension wire and clean the top of the coil with alcohol. Clean the wire and dust boot as well. Apply dielectric grease to the inside of the dust boot at both ends where it touches the coil and the wire.

[Zed Head]

Just registered for me what you meant by arcing from center to negative post. Brain not working right earlier. Still bad, but beerman and SteveJ have the solutions.

[26th-Z]

I concur with SteveJ and Beerman. The insulation is cracked.

[Duffman]

Thank you, everyone, for your input. Based upon the fact that the wires are new, and I was the one who cut the custom length spark plug wires, I believe the issue was caused by me (big surprise!). I always felt that one or two of the wires were cut a tad short by me. I installed a spark plug wire holder over the thermostat housing Monday, moving the wires around slightly, and this problem started. Am thinking one of my wires needs to be lengthened to assure proper contact with distributor. Will pursue and let you know the results.

[SteveJ]

That sounds like a good start.