Factory Five Racing Forum banner

1 - 11 of 11 Posts

·
Vegasjack
Joined
·
84 Posts
Discussion Starter #1 (Edited)
Arcing problem with #6 spark plug.

I have a 1989 5.0 in my Mark3. The #6 spark boot sits very close to the header pipe. It actually burnt the boot a couple times. I have been able to move it so that it is about 1/8 inch from the pipe, but now it wants to arc over to the pipe when running.

I am sure I am not the first with this issue, so was wondering if anyone had a resolution to the issue. I did search this site. Several posts on that plug burning on the exhaust, but didn't see any on arching to it.

Has anyone experienced this issue and how was it corrected.

Thanks, Jack
 

·
Registered
Joined
·
49 Posts
Maybe a strategically placed dent in header pipe.
 

·
Registered
Joined
·
49 Posts
And/or insulating wrap in that area.
 

·
Registered
Joined
·
178 Posts
In the electrical industry you can get sleeving of various diameters that are silicon coated over a fibreglass matting composition . Not something you would find at your average electrical wholesaler, but commonly used by motor rewinders. They have excellent insulating and thermal properties. I have seen a similar product used to protect flexible hoses on fire suppression systems in heavy equipment.

Cheers Nigel in South Oz
 

·
Not a waxer
Joined
·
11,764 Posts
What boot configuration? Straight boots often get very close to the tube and are vulnerable to heat damage and arcing. 45 degree boots (sometimes called 135 degree) can usually be positioned to locate the wire midway between the tubes.

Jeff
 

·
FFCobra Craftsman
Joined
·
22,705 Posts
Replace the wire. The insulation properties of the silicone are done. Same as Jeff, I switched to 45 degree ends and haven't had a problem since. When I first bought my FFR it came w/ very nice wires from a major brand. I saw that a couple were touching the header sometimes but figured it doesn't seem to be hurting anything as I twisted it away to get a tiny clearance. 2yrs later I started getting a miss so I fired the engine up in the dark. What a sight! 2 wire boots had been dried out so badly they looked like a hard packed piece of desert. Silicone works for a while but not forever.
 

·
Too Cheap to paint!
Joined
·
6,218 Posts
Like everyone else and the OP, I too have burned spark plug wires. Different longer boots I could bend, Insulated covers, wire routing.

I used something like this over the plug boots: https://www.jegs.com/i/JEGS/555/40304/10002/-1

Repair or replace that wire, re-route and add protection, and happy motoring!
 

·
FFCobra Craftsman
Joined
·
22,705 Posts

·
Buck
Joined
·
289 Posts
I went with the Taylor 135 deg wire because the straight ones are too close to the header and allow you to position the wire away from the header tubes.
Buck
 
1 - 11 of 11 Posts
Top