My brother's 69 Z stalled on him the other day and smoke came out from under the hood. He opened the hood to find that the pigtail wire from the positive terminal to the junction block was glowing red and had melted all the insulation off. Also, the headlight harness had melted the black tape off, but the wire insulation itself was OK. This happened when he got on the gas pretty hard and revved up the engine pretty high in gear. Headlights were off.

He replaced the positive cable (with pigtail), junction block, voltage regulator, and horn relay with parts from another car that he has stripped down to restore. He revved it up in neutral pretty high and had no issues. Took it for a spin. and once he hit about 4K rpm the same exact thing happened again.

Electrical systems aren't either of our superpowers, and I googled the issue as many ways as I could with no results, so I thought I'd ask this forum if anyone has had this issue and knows how to fix it. This is the 5th first gen Camaro he's owned and he's never had any problem like this before. Anyone who's driven a Z/28 knows that you can't drive it around under 3K rpm all day! We need to figure this out so he can enjoy bringing his kids to school again and annoying the other parents in Pruises with his chambered exhaust...

Thanks for any advice.

 

Mine had a 37 amp alternator is all IIRR and when driving one day mine did the same thing
It was my Fosgate amp asking too much from the alternator and it melted the wire to the battery and half the power wires in the car
Replace them all (use bigger wire)
See how big the alternator is, I think I switched it to a 55 amp IIRR

I had to sell it to finish getting rid of my X wife. Best deal I ever made!

 

Thanks, manicmechanic. His car is totally stock. Repro stock output alternator and no big power draws like aftermarket stereo, etc. My guess was that the regulator wasn't regulating and to much power was being put through those wires, but he swapped out the regulator and it still does the same thing at higher RPM under load. Strange.

A little about his car: it's an early build '69 Z (1st week of October 1968), and it has a flat hood, no spoilers, no console, no tach, manual steering, and no options other than a fold-down rear seat and chambered exhaust. Frost green with black stripes and a black standard interior. It had been a drag car when he got it, with some crappy homemade wheel tubs, scattershield, deep sump oil pan, and a giant Sun tach on the steering column. Fixed all that back to stock and now it's for cruising around town.

By the way, this: "I had to sell it to finish getting rid of my X wife. Best deal I ever made!" is hilarious. I just had to sell my house to do the same thing - totally worth it!

 

Well, it does have the special bigger alternator pulley right?
Somehow it must have full fielded itself and reached max output for an extended period of time
That can happen with a loose battery connection or terminal end
I scraped by with my Boss 302, a pair of shorts and a 3 wheeler IIRR
Mine was quite a while ago so I am all better now
You can still get a big boss alternator pulley so if you don't have or cannot find the special Z one, you could use one of those
Mine would do 60mph in first with a 3,73 ratio and stock size 15 inch tires
If your 302 turns R's like that you need that pulley

 

Look at those battery cables close
The previous owner who raced it must have also had the big pulley
Maybe the wires are hard and have resistance which builds heat and more resistance

 

Yes, it has the larger alternator pulley. He has been driving this car for years and now all of a sudden it melts the wires when you rev it. I was hoping someone on here might have had this issue before and know what the fix is.

 

Well, the answer is to see exactly what the charging system is doing and why
You need to test the alternators actual amperage output with a VAT 40 or equivalent tester
You need to test the voltage while testing the output as well
I would think you need another new voltage regulator
Good luck with other answers
The usual reason for one full fielding itself is no communication from the battery showing the alternator the state of battery charge
The other one is welded points in the old style regulators

 

Thanks for those details. The fact that it only happens while the car is in gear is going to make it tough to test.

One interesting fact is that once the issue happens, even after the car is turned off, the pigtail wire continues to burn red and sizzle until the wire is cut or otherwise disconnected. This makes me believe that some type of short to ground is occurring. The short is being triggered by something but then continues even after the car is off.

Looks like we are going to have to find someone local who knows analog car electrical systems.