[Sirrotica]

One of the constant failures in HEI since GM started using them is the white and green wires that go from the 8 toothed pickup coil/pole piece, to the module. Every time the vacuum advance moves that unit, it twists the wires. After so many movements the metal core in the wires becomes fatigued, and breaks a few strands at a time. Eventually the wire is down to a few strands and won't carry current, and failure happens.

Grab the insulation on both of these wires (green, and white) and give them a good yank. If they are frayed they'll rip off, you've found your problem. Sometimes they'll make the ignition cut in and out before they fail, but not always, sometimes they just shut off the ignition without warning, never to restart again. Any distributor with 50,000 miles on it should be suspect, sometimes they fail sooner, sometimes they go 150,000 miles and never fail.

I've seen numerous wire failures on the pole piece, I always test the wires if the ignition is suspect to a no start condition. I've seen most ever component in HEI s fail, this is one of the most overlooked pieces, because it isn't easy to change. The distributor has to be removed, and the shaft has to come out to replace it, so in the way parts changers assess a problem, they by pass it because of the complexity of changing it. It can't be changed with just 2 screws, but you can easily test for broken wires by yanking on them while the distributor is still in the engine.

Another well known failure point is the rotor, it burns a hole from the thin contact strip right through the plastic to ground out the spark of the shaft. You'll likely see a faint rainbow colored stain if you raise the thin contact up with your finger, and examine the plastic in the center of the rotor, it can also be seen if the rotor is removed by looking at the bottom, center area. The early black rotors were especially prone to burn through, the white redesigned ones were less prone to burn through.

Any, and all of the components can fail, and I've seen all of them fail, but the two examples I've posted, are sometimes overlooked. There are of course tests for most all the HEI components done with meters, however backyard mechanics usually resort to replacement, rather than testing. Keep screwing parts on, until it starts. That can get expensive, but if you don't have knowledge, or the tools, it requires little effort.