Cylinder #5 will not stop arcing off header!

[4xcrazy]

If what i'm reading on here is what i think it is, i had a similar issue several months back, after awhile, the spark jumps through the boot and grounds out on the headers, i kept swapping out boots, getting new wires, finally i changed out the spark plugs and i believe, the problem went away.

What i was thinking is maybe for some reason the electrode inside the ceramic of the plug was broke or something, causing that plug to generate more heat than normal, overheating the wire boot.

Just a thought, nothing actually determined or factual about this, just know the plugs were changed and i haven't had this problem since.

oh, and a friend also gave me a set of those plug wire shields before i swapped out the plugs and it still happened, the arc just went through those too.

 

[4X4HIGH]

Like i said, the problem is too much resistance since the boot and or wire isn't actually melting from too much heat. Electricity follows the path of least resistance, in this case arcing through the boot or wire is less resistance than the probalem at hand. I've already suggested changing the plug which I suspect to be the issue.

 

[Blue85]

Like i said, the problem is too much resistance since the boot and or wire isn't actually melting from too much heat. Electricity follows the path of least resistance, in this case arcing through the boot or wire is less resistance than the probalem at hand. I've already suggested changing the plug which I suspect to be the issue.

So if the spark plug is plugging the spark, is it doing it's job?

I agree that there could be something wrong with that spark plug, but surely he has replaced the plug or swapped some plugs around by now. Even with the center conductor and end electrode broken right off, the boot should not experience dielectric breakdown. It doesn't look burnt, but it has either been burnt or the design is crap to begin with. You should be able to hold any part of the plug wire (or boot) against the block anywhere without arcing. Otherwise it's not even safe to reach under the hood.

If there is high resistance, I suspect the crimp from the wire to the terminal or the clip of the terminal on the plug. Maybe the custom-length wires are to blame. And if it's arcing in there, that could be burning the boot from the inside out until it's able to arc through the insulation. Once you have a pin-hole in the insulation, that path is lower resistance than the tiny gap in the spark plug - when the engine is under load.

And BTW, electricity does not follow the path of least resistance. It follows all paths in inverse proportion to their resistance. But when you have one path with drastically lower resistance than all others, the current through others becomes negligible. Why does it matter? Because the resistance through the plug gap changes with compression, temp, etc. and the ignition current can take different paths based on the changing conditions. So while some sharing can take place, whichever path ionizes quicker will take most of the current.