I've owned my '76 teener for about twenty years. I recently installed BlazeCut in the engine compartment to hopefully stop any potential engine fire.
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I took the car out for a short test ride soon after completing the BlazeCut install. As I was headed back toward home, suddenly thick black smoke started pouring out from under the dash in front of my left leg! I quickly pulled over and shut the car down before a fire started. After the smoke stopped and my heart slowed down, I lowered the relay panel and here's what I saw! After forty years, one of the of the relay bases somehow short circuited internally and melted the surrounding rubber.
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I finally got the car home and repaired the melted relay base and all is good now. But I remember what I was thinking when I first saw all that black smoke coming from under the dash. "Great, I have a fire suppression system mounted right behind my back, and the car is going to burn up in front of me in the passenger compartment and there's nothing I can do about it!". I now carry a small fire extinguisher in my center console box, just in case!

Wow. Glad you're safe!

I'd be a little concerned that there isn't a short somewhere. Relays can go bad, but they usually just fail. Next time you drive it see if that relay feels really warm. Great idea to have a small fire extinguisher in the cabin regardless...

Wow! That was one lucky save. Good you got it in time. I think that was a pretty weird short to happen where it did. I can easier see a wire rubbing on metal somewhere but an internal short in that connector is something else

Stuffing a blazecut up inside the dash wouldn't be that difficult and they aren't very enpensive. This would be a great idea for guys who have their cars torn apart.

Which relay was it ?

Thanks for everyone's kind comments about my status! It was the relay on the far left side of the board, I think that's the horn relay. It seems that the short was internal to the rubber relay base itself. There's was no sign of any shorting to the board or anyplace other than inside the rubber base. That's what I repaired, and now the relay that was plugged in here and everything else on the car works fine after the fix.

I'd stick to a fire extinguisher on this one. The blaze cut hat to have a significant amount of heat (think damage) before the plastic shell melts. It's a last ditch effort to control the fire. You should always carry a fire extinguisher. Preferably not a dry chemical one as you'll have to disassemble everything if you use one of those as the chemical is bad for your engine.