Keep Blowing Ign Modules

[gmtofd]

Hi,

This problem with blowing HEI modules has been going on for a few years, on my presently totally stock '79 with the 267 mtr. They generally last about 1,000 miles, then no-starto.

I've swapped, coils, distributors, added a ground from the dist housing to valve cover bolt makes no difference, modules keep blowing.

Well, we're presently down to a single driver, for my wife and myself, until I find something for her and was looking over the body ground to back of head connection. Sure enough it was loose. Thought that I was finally home free with the problem.

This morning, took it for a 20 mile or so parts chasing run, getting the Malibomb back, so she could make her hairdressing appointment. She gets in cranks it and no-starto once again. Go thru the now 10 minute module swap routine and still no starto, do it again with the last good module that I had, same deal .

During the summer a few years back, had to r&r the ignition switch and brought a Pep Boys Chinese pos. Seems like 3 or 4 thousand miles later, is when the first module blew.

Back to basics, key-on, 12V, Voltage while cranking was at first about 9.25 then increased to about 11.25. Does anyone know it this is normal?

Thanks for any responses.

 

[bowtie81]

When you put the new modules back in do you put any di-electric grease under it? just a thought it may be arching in there. i know when i used an msd module it calls for using the grease under it.

 

[Doober]

Do you have a tach hooked up?

 

[NOT A TA]

A good module should come with a small disposable tube of "Heat Sink Silicone Compound" which should be generously applied to the bottom of the module. The compound draws the heat out of the module to the plate it sits on (which should be clean). Failure to use enough compound seriously reduces the life of the module.

 

[gmtofd]

Thanks for the return posts.

Yes, using the correct white head conducting grease.

Was hoping someone would know the range the ign switch voltage is suppose to be while cranking. As was posted, checking it this morning, it varied from 9.25 to 11.25 V. Going to check it again with another meter.

First will try easy thing tomorrow, swap out coils.

 

[gmtofd]

After searching for awhile, the problem seems to be nothing more than a loose wire at the coil hot lead connection where the ign switch 12V feeds the coil. Presently the module, when the no-start occurred is back in the distr.

To recap, because of a loose body ground, and the constant module replacement loosed the coil connection.

 

[bowtie81]

glad to hear you found and kicked that gremlin out.

 

[NOT A TA]

A free fix is a good fix! Glad ya found it!

 

[liquidh8]

Glad you fixed it. The family chevy c20 eats modules. Every once in a while one of us (me, brother or father) would come out and no start. I never found it. different engine, dizzy, coil, new ground, etc. I just keed a few spares in the glove box, the truck is only used to haul parts, home depot runs, and the car trailer.