While starting my '71 the other day, I heard a loud pop, saw a puff of smoke over the intake area. I also smelled burnt wiring. Looked all over, but could not find any burnt wires. My MSD coild was making a really weird noise, even after I had disconnected the battery. I figured the coil must have fried, so I replaced it, and the new coil is making a buzzing noise too.

Also, when you rev the car above 3k, the tach momentarily drops to zero, then bounces back. I am sure that is related to what is going on in the coil.

I am using a Pertronix. Everything else is stock '71.

Any ideas on where to look into this?

TIA,

Marty

That's jsut scary. Don't stand too close in case it bursts on you. Hot oil is not a very nice thing to have sprayed on you or in your eyes. I have no idea what could cause that but hopefully someone can help. I'd check for a short somewhere. Perhaps the low side terminals are shorting out or something like that?

Update on the coil buzzing. I still have not found the actual cause of the buzzing. One gearhead buddy said that it is likely the oil inside boiling from overheating.

I changed the ballast resistor and so far it seems that the buzzing has stopped. My tach still drops off after revving up to about 5700.

I have checked all the wiring and the grounds look good.

Any ideas on why the tach drops off?

TIA,

Marty

Here's the resolution to close this one out.

The new ballast resistor has seemed to fix the buzzing sound.

Over the weekend, I pulled the optical sensor in dizzy to clean it. Three of the magnets fell out of their slots. I put in a spare that I had and the tach now pulls smoothly to 6K. So if you see this issue, clean the sensor and check the magnets.

Marty