Plug wire question
Thread Starter
Instructor
Joined: Aug 2001
Posts: 150
Likes: 0
From: Jacksonville FL
Plug wire question
I'm busy hunting down a possible fuel, spark, and/or vacuum related problem in my '77. Last night I opened my hood, after a highway drive, while the car was idling to see if anything was arcing. What I noticed surprised me...the majority of the spark plug wire boots at the plugs were lighting up. Is this normal? Does this mean the majority of my plug wires are bad or are the ones that aren't lighting up, or lighting intermittenly, bad?
The boots themselves didn't seem to be arcing to anything but the spark plugs. This still didn't seem normal because I thought the only arc should be at the gap of the spark plug. Any idea what I'm seeing?
I've got the stock 8mm wires and stock ignition system.
Thanks,
Ted
BTW I replaced one of the "lighting" plug wires and the new wire lit up even more than the old. Strange.
[Modified by love to drive, 5:49 PM 4/10/2002]
The boots themselves didn't seem to be arcing to anything but the spark plugs. This still didn't seem normal because I thought the only arc should be at the gap of the spark plug. Any idea what I'm seeing?
I've got the stock 8mm wires and stock ignition system.
Thanks,
Ted
BTW I replaced one of the "lighting" plug wires and the new wire lit up even more than the old. Strange.
[Modified by love to drive, 5:49 PM 4/10/2002]
Race Director
Joined: Nov 2000
Posts: 11,872
Likes: 12
From: Waterloo ontario Canada
Re: Plug wire question (love to drive)
Are you saying that the spark is running down the outside of the plug. Oil or paint of the plugs could cause this. If it is fact running down the outside of the plug then it is not a wire porblem. Replace the plugs with new. Bad wire boots show up as arcing to the exhuast manifold, this is bad boots. Bad wire arc anywhere so replace the wires.
Drifting
Joined: Jan 2002
Posts: 1,645
Likes: 11
From: Schaumburg IL
Re: Plug wire question (love to drive)
No question - when you can see the glow at night, there is serious spark leakage. I did not read your post real close, do you have headers? If so, the heat will break down the silicon glue and cause spark leakage. Replace them with a quality set. Recommend Accel 300+ race custom wires or the new 8.5mm MSD wires. Both have <500 ohms per foot for max spark and min. RFI.
Melting Slicks
Joined: Dec 2000
Posts: 3,407
Likes: 2
From: Carmichael CA
Re: Plug wire question (love to drive)
It's not uncommon to see a "slight" glow where the wires touch something steel that is grounded, however a good set of quality wires will not have any glow.
But, you indicated that the boots are glowing...this is an indication that the wires are not attaching snugly to the spark plugs, and not an indication of bad wires. Pull the wires off the plugs and clean up the contacts, use some needle nose pliers to tighten the noose on the end and try them again. If they "still" persist in arcing then you may need to remove the end completely and cut the wire back about 1" (if there's enough wire for it) and reconnect the end. If that doesn't work, then buy yourself a set of good wires.
But, you indicated that the boots are glowing...this is an indication that the wires are not attaching snugly to the spark plugs, and not an indication of bad wires. Pull the wires off the plugs and clean up the contacts, use some needle nose pliers to tighten the noose on the end and try them again. If they "still" persist in arcing then you may need to remove the end completely and cut the wire back about 1" (if there's enough wire for it) and reconnect the end. If that doesn't work, then buy yourself a set of good wires.
