Today I was under the car trying to find my oil leak. I was using a flashlight (car was running) and I saw one of the plugwires arcing off the header. It was the plug boot making serious contact with the header. The boot was a little melted, but the arc was a "bright" blue. The car was running great last night, then all of the sudden it felt like it had a miss. Is this a symptom of the plugwire making contact with the header? I fixed it, but it is raining, so test drive was out of the question. It is a very tight fit on that particular plug (#4). I think it is ok now.

Although your boots or leads can handle considerable heat, Prolonged heat will detroy them, make them brittle and they crack forming an easy path for grounding.

Unless you are able to buy angled boots and/or buy heat sleeves for them, or modify/replace your headers, you can expect this re-occuring problem. You must provide an air gap to reduce the heat transfer.

These will help, but if they still touch the headers, they will only buy you time.

http://store.summitracing.com/egnsearch.asp?Ntk=KeywordSearch&DDS=1&Ntt=boot+plug+heat&searchinresults=false&N=+115

http://static.summitracing.com/global/images/prod/large/msd-3412_cp.jpg
or
http://static.summitracing.com/global/images/prod/large/tay-2528_w.jpg

I'll check those out. Since mine was arcing pretty good, is it possible that the #4 cylinder wasn't even firing, or getting a weak spark.

I'll check those out. Since mine was arcing pretty good, is it possible that the #4 cylinder wasn't even firing, or getting a weak spark.

Absolutely. Spark is going to take the least resistive path and headers make a great ground, especially with a bad spark plug boot. Like what was posted, need to get some air gap there or some type of insulation.

Accel also makes header plugs or 'shorty' sparkplugs that are about a 1/4 inch shorter than standard plugs. This gets the plug far enough away from the header so it doesn't arc. They worked out great on my sons car.

Mark

Once an arc has been established, there is a low impedance path through the insulation of your wires that is permanent. The only way to remedy the problem is to replace the wire.

I've had to fight some with plug boots touching headers (hooker comp 1 5/8", w/angle plug heads)

If you have to buy new wires, get Taylors, period.

The accel shorty plugs helped a lot in getting some clearance but it was still neccessary to "adjust" a couple tubes with a Ford tool to eliminate contact.

Note that even after several months of hard contact with the headers prior to me fixing this, the Taylor boots did NOT burn thru, the engine never missed, and I did not replace the 2 wires that were in contact.