What causes this

[Tulsa76bronco]

Was doing other things in the engine and this fell off this wire is only 3 years old at most what causes it to be so black and become brittle

 

[thegreatjustino]

Looks like it was riding on your headers

 

[blubuckaroo]

I've seen that happen.
If the carbon conductor is damaged, the resistance will heat up the wire and burn it out.

 

[B RON CO]

Hi, yes, it looks like it was arcing. Is that the wire to the coil, or a plug? It looks like the short coil wire. If so pop the distributor cap and make sure all is good and clean on the cap and rotor. Maybe someone pulled on the middle of the wire instead of the very end and damaged the terminal. Good luck

 

[September 1972]

Off shore parts and /or mismatched coil and/or HV output excedded the capacity of the core. Change the wire but don't do anything else and keep an eye on it. good luck. most of us have far worse problems!

 

[sykanr0ng]

That kind of wire can be damaged by bending them then the resistance will cause that.
Even US made wires back in the day would fail like that.

 

[Rustytruck]

Just a cable not plugged in all the way can cause that. An arc jump causes allot of heat right away. Any engine miss needs to be dealt with right away.

 

[Steve83]

...what causes it to be so black and become brittle

Heat.

It might have started with a cheaply-made wire; or a loose terminal; or you didn't snap it fully down onto the terminal. Or it could have been external heat, like from headers or an exhaust leak blowing onto it. We'd need to see its installed location, and to know the brand/PN/source, to help you figure out what caused it.

Click this & read the caption:



One of the thumbnails at the bottom will take you to a photo album that shows how to repair a plug wire.

 

[Tulsa76bronco]

Good stuff

Here is a pic has been hooked up like this for about two years no problems and the top holds it right, I just put one of my old ones on for now until I can get another red wire. As u can see made in the USA

 

[Steve83]

I prefer US parts because they more-directly support our economy, but that doesn't mean they never have flaws. My guess is that one wasn't built right, and eventually, it burned out there. I'll continue avoiding MSD parts.

 

[Tulsa76bronco]

Do any of the parts stores just sell small amounts of the coil wire or on spools to cut off. I had purchased all these in a pack would hate to have to buy an entire pack just for one wire

 

[ledslinger29]

As mentioned above, if the inside of the wire is burnt it is due to high resistance, which is caused by a wire break or a poor connection.

 

[Slowleak]

Do any of the parts stores just sell small amounts of the coil wire or on spools to cut off. I had purchased all these in a pack would hate to have to buy an entire pack just for one wire

Here's a red one.
https://www.summitracing.com/parts/...4JCNhNQCFdc8gQod4t8DUA&ibanner=MobileSwitchNo

 

[Steve83]

I doubt any local parts store would stock even one spool of spark plug wire; much less, a choice of colors including red 9mm silicone. I have an antique spool of gray ~7mm that I inherited from a guy who restored old British cars, but if I wanted a spool of silicone, I'd shop eBay & Amazon.

 

[Slowleak]

https://shop.advanceautoparts.com/p...ingcampaigns&gclid=COPFts2jhNQCFYY8gQod4XcD5g

 

[Yeller]

Grand Prix at Admiral and Yale should be able to help with 1 red wire.