Howdy. I've got a small-block 350 in a 72 Malibu. One day the car wouldn't start, with no real warning. Since everything on it was original or at least very well used we figured it might be the distributor giving us problems. The distributor was upgraded to HEI, a new coil was installed, and a 4bbl intake and carb was put on too.

With the installs completed we tried starting it up. It sounded as if a few cylinders fired, then we weren't able to get anything out of it. Using a test light we could see the coil was getting power from a purple wire. (I had read something here about HEI needing a full 12V and the purple or yellow only carried 9V.) We moved the coil wire close to the headers, and the coil didn't put out a spark.

We replaced the new coil with the coil that was previously on the car. We took the coil wire and placed it near the headers. There was a spark when cranked. Then we tried to start it. The car fired up and ran. Bad coil we thought. We shut it off for a while then tried starting it again and got nothing. Heeding the advice of a power shortage to the HEI we wired the coil to the ignition on the fusebox. Nothing. We checked spark out of the coil and there was none. On a hunch we dug up an old coil we had lying around and hooked it up. We tested for spark, it was there. We started it up and it ran.

I tried starting it a few days later and it started. But, after turning it off it wouldn't start again.

A few days later, today, the car still won't start. It fired a few cylinders when it was first tried but gave nothing after that. Taking the coil wire and putting it near the headers, no spark from the coil.

I'm willing to bet if we took this new coil down and got a replacement, that replacement would run the car for one good run, then die. There's a pattern here but we have no idea why it would do this. The car just seems to be eating coils.

Wiring changes:
purple and yellow wire disconnected from + of coil.
proper sized wire run to ignition on fusebox from + on coil

Thanks for any assistance. I'm really stuck.

Edit: Well I feel foolish. This isn't an HEI distributor. It's a Pertronix Flamethrower, which replaces points. Would I need to put the resistor wire back on?

Yes

Coils definitely fail, so a new one is a good move here.

No clue on Pertronix, but try their website for a wiring diagram of how it is supposed to be connected. Also get their troubleshooting procedure to check the module.

My guess, is that it connects to the coil the same as the points did, with 12v in the start postion from the starter solenoid, and power via the ballast resistor in the run position. You are correct that HEI only needs one 12v source for both the controls and the coil. Not sure what the pertronix needs for power, but a guess would be 12v in both start and run.

Also need to check stuff like the wires and connectors to make sure that a frayed wire is not causing this. Two strands will start the car cold, but it will not carry enough current to keep it running or restart hot. I have experience in this.