Spark plug wire boot ends, problems

[4xcrazy]

Anybody else having issues with spark plug wire bot ends getting soft from exhaust manifold heat, breaking down, then letting spark arc out onto the manifolds?

I was having this issue awhile back with my '89 Burb, TBI 350, two or three would do it all the time, requiring replacement. That one would only give me a few days at best. I thought it was due to some crushed exhaust tubing on a previous wheeling trip that was maybe causing some serious back pressure, heating up the manifolds or something... But now I have this '87 with the same engine setup and just had to go out and replace the wires due to this same issue.

Cylinders 6 and 7 on this one, this time. I'm not sure if it's going to be an ongoing problem, as this is the first time I have had to change out the wires set.

I'm just wondering if it's the manufacturer of the wires, I bought them at a local parts store that offered lifetime warranties on them, or if something in the engines are causing manifolds to heat up higher than normal. The factory heat shields are still in place.

They say they are high temp 8mm silicone wires.

 

[dyeager535]

I've been running the same set of Accel plug wires on my truck for about 10 years now, and only lost one but that was not due to the boots.

I've got headers, and I know this thing has run quite lean in the past, so they've been subjected to a lot of heat, besides being right next to the primary tubes in a couple of positions. I don't put many miles on it a year, but they've maybe got 40K on them.

The plug positions that are failing, are they near the dump on the manifold?

 

[black dawg]

are they the blue napa belden wires? They seem to be more sensitive to heat than the older wires.

 

[4xcrazy]

The manifolds in both trucks are the factory W shaped ones, sort of, the manifolds exit downward and connect to a bottom tube. I have headers on the '89 now because I thought the crushed tubing was the problem, also added some of those Kevlar heat socks, when it was running, I hadn't had any other issues with that truck.

No, they are not the Napa wire sets. These are dark grey, black boots. I'm almost embarrassed to admit where I bought them from, so that may give you a clue..

 

[4xcrazy]

No heat shielding on this one, but the one I saw for sure that was damaged was on the passenger side, that one does have shielding on it. Not 100% sure it was #7 that was the other one either as I didn't notice it till I pulled them all off, all I remember now is that it was a shorter wire. So it very well possibly could have been both 6 and 8 that were causing problems, and that's the same side I had problems with on my '89.

 

[dyeager535]

Only reason I'm running anything other than parts store cheapies is that I needed to make my own length wires. May have to go back to "stock" ones as the aftermarket build-your-own plug wire sets seem to have gone way up in price.

The one wire I *did* have to replace is probably a parts store piece, I made no effort except the minimum to get the truck running again. One of the reasons I no longer throw away "working but unknown quality" plug wires.

 

[4X4HIGH]

Go buy yourself some of the MSD boots, they are good for 1200* and i've never had an issue with them.

 

[80' 427]

It isn't running in open loop or something dumb is it?

 

[chulisohombre]

I run mad 8 mm wires for about 8 years and no problem. Even with headers. The cheap store brand ones never last more than a few years at most that I've seen.