Have this posted in the engine section, thought maybe someone in this group may have an idea or two.

burning out distributor modules.

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Car is a 1988 GTA, 305 TPI, basically stock except for a 1993 LT-1 cam and 1.6 roller rockers. I keep burning out distributor modules. I replaced the distributor with a billet one, same problem. I have tried the grease that comes with the modules, silicone dielectric grease and the white thermal grease. I have tried different coils (GM, MSD and Accel). Plug wires are new Taylors, cap and rotor are new , with brass terminals. Plugs are the stock Ac Delco's. Wiring to distributor looks good, no apparent damage. Originally, it would fail if I leaned on the gas after running for about a 1/2 hour. Car would accelerate, then start misfiring and die. Wouldnt restart, had to be towed home. This happened twice. I recently installed a rebuilt GM distributor with a new module and pickup coil. Been running for about 300 miles. Out cruising today for about an hour and was running about 40 mph. Car started to miss and died. Bad module again! Fortunately, I now carry a spare module and some tools. A week or so back I had the car idling and I used my IR thermometer gun and the temp at the base of the distributor was 145 degrees. I am running a 180 degree thermostat and the fans work correctly. ECM is a rebuilt from GM, less than a year old. Is there some way to test/meter out the damaged module to see which line is failing? Could I have a wiring issue?
Additional info, the plugs are AC Delco R45TS gap is .045". Wires are the Taylor Thunderbolt 2. The latest module that failed was an AcDelco.

 

I think maybe your gap should be 0.035 not 045. Too wide a gap can do what you are experiencing. Try the smaller gap and see what happens.

 

Well, I've only EVER had one fail !
All of the modules I've ever seen fail, were due to either just plain age ( 20+ years ) or improper heat sink grease.
You want just a LITTLE of that. The point is to aid heat transfer, nothing more.

I run plug gaps nearly double the spec, so that's not it. ( and theory says would cause arc-through and destroyed coils, not modules )

If/when a module seems to fail, I'd be immediately checking the heat at the module !
Although I *have* run 'em near 200 degrees, the cooler the better !

Theoretically, a poor ground at the coil could cause this, though I've never seen that.

 

Found something interesting today. I was reading thru the shop manual, ignition section, and saw a note that states you should not allow the TACH lead to be grounded. I remembered seeing a repair in the TACH lead. Sure enough, it was out of the plastic loom and had exposed wire strands. I taped and replaced the wire loom and laying right next to the valve cover. Plan now is to replace both the coil and module since the manual stated that either or both could be damaged by the grounding. Time will tell.

 

I'd run it a while, first !
If the coil was "damaged" it'll fail completely when hot. Hard starting would be another symptom.
The module should either work, or not. I'd carry a spare, but I wouldn't replace that either, until I knew it was bad, or had definitive proof of a problem, such as replacing it at the side of the road, and have the thing go from a problem to running perfect simply by replacing the module.
But, that's me.........

 

Good point. Only thing that makes me a bit concerned is that this coil was installed just prior to the problem first showing up and the problem doesnt appear until the engine is hot. I have the module swap out down to a science, coil is a bit different, but I would just need a few more tools (or a support car following me LOL). Wont be doing much more driving up here this year so maybe taking the chance is the easiest approach.