I was out working on my car the other night and it got dark before I went to get a light. I'm working on carb and I look up slightly at the coil for some reason. I noticed two constant lines of spark jump from the negative side to under the rubber cover to the wire in the center(goes to dist). Never noticed it before, but it can't be right. Could this be why sometimes my car idles normal, and other times it idles low? I think that's mainly an intermittent vacuum leak, but wondering if an electric jump like that on coil could cause weird problems.

Tony
'68 Chevelle 400

I could see that causing an eratic idle, BUT it could serve to decrease the amount of 'juice' put out to your plugs. and with some not-so-good plugs this would not give full combustion and therefore casuing a 'weak' idle.

You did replace it as well as the wires right?

Checked for a vaccum leak, can't find one. I did put in new accel u-groove plugs and wires, still got that coil on there. Just to test something, I sprayed some silicon on the negative terminal of the coil and some of the hestitation went away and she seemed a little stronger. Points are still old(at least 10 yrs that I know of), and still trying to get the darned new set to work(done before, just fighting me). Gonna go pick up coil and get a new set of points, as others could be defective. Glad to see that could really hurt how she runs.

Tony
'68 Chevelle 400

Oh. I thought maybe you were very good friends with Force's crewchief (kidding).

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von '69 300 Dlx SS TC #15 ACES #1575

Ox68 if your seeing spark out of your coil, chances are the coil has a hairline crack in it. Take it off and check it , i have seen this happen a lot.

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CFR.

If you'r seeing a big hefty spark this engine should not run at all.Sometimes you will see a kind of glow type spark this is not unusual.Next time take a look at the plugs you will probable see the same thing.Just wipe every thing down this can be caused by moisture and dust particles.This is the way one of those timming lights work that pickup through the wire its called induction leakage, (I think)Some one correct me if I'm wrong please...FRED

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It was kinda weird, but not as much a glow. The end that goes under the screw on the negative terminal goes past screw on other side some, towards inside of coil. It almost looked as tho the spark was coming from them. The jump of electricity looked just like little lightning bolts. Two very distinct lines.

While we're on the topic of coils, I seem to have an extra wire. I know the distributor-points wire goes to negative, as would the tach if it was hooked up. I could have sworn 2 wires, and that resistor on the back of the coil bracket went to positive. Is my thinking right?

Tony
'68 Chevelle 400

I had this electrical show under my hood last month. I had replaced my spark plug wires with stock wires a year ago, and while attempting to diagnose the idle hesitation and surge, before my eyes was this errie blue and yellow light show! Two of my plug wires were grounding out to the exhaust manifold and my coil was acting like a lightning rod. Whenever my engine hesitated, I noticed and heard a large healthy spark jumping from the plug to ground. Also the plugs were experiencing flashover on to the porcelene. I felt like screaming outloud "It's Alive!"

Replaced wires to Taylor 9mm and coil. No more light show and greatly improved performance and mileage.

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Joe G.
ChicagoChevelle68
Any car past 1972 is just transportation.
josephguzman@yahoo.com