After 5 years restoring my car it is finally at the upholstery shop for the new top and interior. In the process of running the top up and and down to fit the new top, the yellow/black wire from the ignition switch to the ignition coil overheated and burned all the insulation off from the ignition coil almost to the fuse box. Not blaming the upholstery shop, but I had the car running several times in the garage and driveway. Also, ran the top frame up and down many times to get it adjusted with no issues. What would cause this wire to burn in the first place and why didn't it blow a fuse or the main circuit breaker?
I really hate electrical problems!

 

Maybe they turned the the key to ignition to run the top up and down for some reason and left it on? I know you can burn up points and Pertronix systems can be fried leaving the key in the on position without it running , not sure about the wire?
There are a few wiring gurus on here, makes my head hurt.

 

If that's the whole story, it sounds like your coil went bad. Ignition circuit on those is not fused.

 

Yep, this is true. The key should not be left int he run position for long with engine stopped.
Points definetly will fried due to the constant current from the coil. When engine it running, the high current is pulsed, so no overheating will occure.
Is this with the stock coil? Wire overheating can occure.
Many "high performance" aftermarket coils draw even more current and can easily burn up wiring that way.
If this particular car uses resistor wire, then it will need to be replaced with the correct resistor wire. If it uses a separate ballast resistor, then regular 18ga wire can be used.

Note that it is possible that the coil could have overheated also and could have shorted also. They are not designed for continuous current.

 

I am using a stock coil. I saw in the shop manual, a diagram of the ignition switch with both power wires going to the coil. The "on" wire is connected to a ballast resistor, then to the coil so the points only get 9 volts when the key is on and 12 volts in the start position. I read in an article about coils, that GM used a special cloth covered resisitor wire that accomplished this. There was a section of a cloth covered wire in the original wiring harness that was spliced to a vinyl covered wire. Unfortunately, there were a couple of wires that had been hacked into and spliced over the years. So it didn't grab my attention. I should get the car back in about two weeks and can pull the harness apart to better assess the damage. Hopefully, no other wires were ruined. And I am going to install a firewall mounted resistor.
Thanks for the replies.