81 dl. My car has been idling a little rough so i bought new ngk plugs and some omni spark 8mm plugwires. It still idled rough and after fiddling with different things i couldnt figure it out. This past monday i had the hood open and the car running. It was dark out and i noticed the number two plug wire shooting spark to the clip that holds the cap on. I figured bad cap or a crack. I looked a little harder and there is tiny real light sparks/arcing everywhere on the wires. I got to looking around and the plugs are even arcing between the part of the plug where you would put a socket to take out the plug and the head. All four plugs do it and all four wires have the random arcing. I replaced the wires with a set of ngk 7mm wires and i still have the same problem. Can anyone tell me how to fix this? I have searched around on here and all i can come up with is new coil. Sound right?

Sounds alot like spark plugs have too much resistance. Maybe wrong plug or too wide of gap. Most of the time if you see an arc between the dist. cap and ground or the coil tower and one of the primary terminals it is bad plug wires and or spark plugs. But to arc from the plug wire across the spark plug insolator is rare. What number plugs did you install?

 

Mark

The plugs are brand new ngk BPR6ES-11's. Gapped to .040 also brand new wires put on this morning. The 8mm wires arced so i replaced with new ones. 7mm and they do the same thing.

Arcs between the plug hexes and the head suggest that the plugs are not grounded to the  heads thru the threads for some reason.

Did you use some type of anti-seize?

 

I would measure resistance between the plug hex and the head for confirmation.

 

Coil sounds fine.

Nope no anti- seize. Just tightened the plugs into the heads. Ill check the resistance tomorrow.

Rereading your post, I see you said it is arcing between the plug base and the cyl. head, not across the plug insolator. I would check to see if the ground strap from the engine to the body is in place, also check the coil braket grounding to the body. The coil is grounded to the body not the engine. There needs to be a ground path between the coil braket and the engine or the spark will try to find a path, like through the air. Think radio.

 

Mark

So, was it the engine to body ground? Or coil to body ground?

Coil to body is good. All the grounds i can find are good. I found one engine ground that goes to the negative side of battery. The battery then has a smaller gauge wire going to the inner fender. I added an 8 gauge ground wire. Still have the same problems. I did some reading on coil wires and found that the coil has two yellow wires on the negative side and two black with white and a solid black on positive side. My coil has those wires. Except i also have a black with red on the positive side. Anyone know what the black with red? I took it off and everything still works. The black with red has no + volt at any time. Its not dark enough to see if i have the same arcing problems. Any help id appreciate.

I think you will find the black with red has power w/the ignition is in the start position.

It bypasses the ballast resistor for starting.

 

Put an ohmmeter between the hex and the head yet?

With the ohm meter between the hex and head. Good or bad?

One observation; not related to your issues - Are you missing a radiator ground.  This is one that connects the radiator to the right upper fan shroud bolt??

Its there just towards the middle instead of the outside

if this is not dead yet i had the exact same problem turned out to be a short in the main engine harness mine was 85 cali carbed emissions weber swapped 

check and make sure you dont have a hot touching the block o2 sensor, fans, ext also by the battery there is a round plug that the main engine harness plugs into that is a common spot from the battery rubbing i had the exact same problem i used this thread to prove to people im not the only one to have this problem mine turned out to be a hot in the main harness touching the block i fxed that car runs fine now try a parasitic draw test probably wont help if your battery isnt dying though

 

Edited August 30, 20187 yr by pbilt