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i replaced the spark plugs on my 302 last week because it was starting to run rough at idle. i found that all the plugs on the passenger side had the wrong gap, (PO doofus) so i figured i had found my problem. well it seemed to run better but not really. i cruised around tonight and the car kept surging and idled really rough at stoplights, neutral seemed to be a little better. well i got home and popped the hood in the garage and turned the light out. guess what?... yep a nice half inch arc from the #8 plug boot to the header, flickering like a blinking beacon. it looked like the heater hose was pushing the plug boot against the header pipe, but the hose can't be rerouted, i suppose i could wire it up or something. does this signify a bad plug wire/boot? or do i just need to make sure that the plug boot, whether new or old, is not against the pipes? right now i think i'm just going to replace all the plug wires. or should i just replace that one wire? or just the plug boot? if that one is old and failed i suspect the others may not be far behind.
 

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Change all the wires, buy a nice set, nice brand, if you could 8 mm 8.5 mm or 9 mm, they work better, last longer......... etc, etc. (MSD, Ford, Taylor, Mallory, Accel.........)
The spark is arcing because the wires aren't in it's nicest shape.
Hope helps
Fer
 
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Many suppliers sell ignition wire boot covers. They slide over the boot to protect it from extreme heat. Check Summit Racing.
 
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Your wires probably are not that good, but also nothing should be contacting the wire or boot. The high flux around a plug wire can induce a current in any metal in its field, including the other wires. If the boot contacts the header, and the inductance is high, the induced current could be high enough to make the arc at that point - as you've seen. If your hose causes your wire to contact the header, you've got to move the hose. If you can't move the hose, replace it with a longer one which you can move.

Dave
 
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