Public Service Announcement: Keep a spare HEI module in the glove compartment!

[Local Hero]

My 77 Grand Prix used to eat those up too. Left me stranded on the side of the road twice and once in the garage.

 

[Bonnewagon]

Here I'm dating myself again. In 1975 when GM switched over to the HEI system, failures and call-backs were very common. The prevailing wisdom at the time was to keep a spare module handy. Although I don't know what good that was without the tools and the talent to change it out. But as time passed the culprit was identified as heat from the distributor body affecting the module. It became obvious because when the engine got cold it started right up. The problem was so intermittent that it took a while to nail down a fix. That fix was the dialectic grease that was schmeared on the underside of the module. From then on, replacement modules came supplied with a little pill of that grease. I have to say that I never experienced a module failure but the pickup coil was my bane.

 

[69hurstolds]

They shoulda been using dielectric heat sink grease.

 

[el camino ss 84]

On my cars never had the modules go bad since I take them out and don't use them when running msd boxes per there instructions. I've had the pickup fail once because a wire can loose overtime due to heat. Thats was harder to pinpoint when it fails especially on the side of the road and it passes the look test but not the touch test to make sure wires are still intact.