pertronix and fried spark plugs?

Engine, Transmission and related drivetrain.
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speeder
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pertronix and fried spark plugs?

Post by speeder » 13 Dec 2018 07:48

Have any of you guys had issues running pertronix ignition and it frying spark plugs?

I've got and LZ22 with an L16 diz in my car. I've been running pertronix for years in there with no issues until recently. The car became harder and harder to cold start. I pulled a plug, and when the plug is contacting a ground, it gets no spark. When you disconnect it from ground, it sparks like it should, suggesting a ground somewhere in the ignition system. I changed the plugs and the problem was solved and the car started easily again when cold. After about 25 miles of driving, the new plugs are now doing the same thing, except for one of them. Put some others in that I had around, and it started right up again.

The coil is probably original. The original appearing ballast resistor is still in position and wired up.
'72 4 door 510, '68 2000 Roadster

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zKars
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Re: pertronix and fried spark plugs?

Post by zKars » 13 Dec 2018 10:05

The plug body has to be connected to ground to get a spark. I don't understand how disconnecting it from ground could possibly result in a spark. Details and pictures will help

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speeder
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Re: pertronix and fried spark plugs?

Post by speeder » 13 Dec 2018 10:40

With the plug connected to the spark plug wire but not grounded anywhere, it will spark in the gap with a big, bright spark, that looks right, when the car is cranked over with the starter motor. When the plug is then grounded by contacting engine or the car body, it looses spark or spark becomes very weak.

Your response may tell the tale- perhaps somewhere in the ignition system there is a ground that is not supposed to be there.

Let me know if more info is helpful. Thanks.
'72 4 door 510, '68 2000 Roadster

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zKars
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Re: pertronix and fried spark plugs?

Post by zKars » 13 Dec 2018 11:40

Love to see a video of that spark plug hanging in free air with nice sparks happening as you crank it. I'd have to believe in magic again.

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Re: pertronix and fried spark plugs?

Post by 510rob » 13 Dec 2018 12:02

Maybe it has a Tesla coil powering it?!?

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Byron510
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Re: pertronix and fried spark plugs?

Post by Byron510 » 13 Dec 2018 19:33

I would agree with Zkars and Rob - you'd need a ground to complete the circuit.

BUT... you point to another issue. If grounded to the motor and you get no spark, that means the spark is going else where - like you have either a cross arc issue or a bad set of wires or cap where you spark is finding a shorter path to ground before it even gets to the plug.... Just a thought.

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Re: pertronix and fried spark plugs?

Post by datzenmike » 15 Dec 2018 14:42

Electricity ALWAYS seeks out the easiest path to ground. Cracked or carbon tracked cap, rotor, spark plug porcelain, or coil tower is a short cut for spark to avoid having to jump the plug gap. What you have to do is make the plug gap the easiest path to ground by insulating the spark away from any other ground.

Image
Crack near negative terminal. Spark would jump to ground. Every time I let the clutch out and pull away from a stop the engine would stutter and often stall turning in front of oncoming traffic. After several years it started back firing so I knew it wasn't the carburetor but an interruption of the spark to the plugs. So I looked much harder and found this. Threw a spare on and it was gone. My '69 Charger was a bitch to start all one winter. Next summer I had the intake off and on the under side of the coil it was carbon tracked. Spark was leaking away.


First, and foremost, are these the factory installed and approved NGK plugs? If not get them.

Second, make damn sure your distributor is VERY well grounded. Everything passing through the coil has to get to ground through the distributor case. A length of wire with alligator clips on the ends will do. Clip to the case and to the block, if the problem goes away make something more permanent.

Carboned up plugs from more choke in the cold weather is usually the cause of hard starts. Spark leaks along the conductive layer of carbon to ground. Changing the plugs (probably cleaner) seemed to help. Maybe your choke is not opening completely?

Has the coil been wired backwards by mistake? The negative terminal should go to the points or distributor. Positive to the ballast. If backwards the spark will be jumping from the block to the center electrode. The ground electrode erodes away faster if sparking is reversed.
"Nissan 'shit the bed' when they made these, plain and simple." McShagger510 on flattop SUs

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