Strange discoloration on header tubes

[funknut]

Header primary tubes on cylinders 2 and 4 have some strange discoloration on the header tubes. very close to where the plug wires are. I have angled ceramic plug boots on all other wires but it was too tight on these cylinders, so I used regular firecore rubber boot 90 deg wires.

Never seen this before today, but did run the car a lot the last couple days. I started to notice a bit of a low idle towards the end of my last drive, possibly a misfire. I’m waiting for it to cool down now before I pull the plugs and inspect further.

You can see a white patch on the primary tube. Headers are steel with some VHT header paint.

Could the plug wire be arcing?

 

[slimt]

Could it be a pin hole?

 

[PRHeads]

That wire routing around the tube like that seems like it would have a negative impact on the life of the wire.

No idea on the mark on the tube.

 

[peabodyracin]

I've seen spark arc leave a mark like that. You should be able to see it clearly if you start it up late eve or when pretty well dark out.

 

[funknut]

Thanks all, I pulled the #4 and #2 plug wires and #4 is cooked for sure. I'll see if I can modify the plug wire brackets to give more space between the wires and header tubes. Not much space on #4 between the plug and shock tower. Maybe some of those fiberglass boot protectors would help.

 

[MoparMur]

Yes the boot protectors work.

 

[MIKESPOLARA]

Looks like the spark is leaking between the boot and the wire grounding on the header. Add dielectric grease in between them. Plus different routing of wires

 

[Brewzer67]

If you get the boot protectors, stay with the white one's. I have seen lots of posts on other sites talking about close calls with engine fires because they were using the cheap Chinese colored versions. The dye they use to color them is flammable and has started a few fires.

 

[MoparLeo]

Reroute the wires. Should go under that tube with a 90° connector. Can you take another pic from farther back so we can see the whole side of the engine ?