Designed to drive HEI module plate...

While it's usually bad form to bump up nearly year-old threads, I think the topic is close enough to warrant it:

I'm using one of these on my '68 Satellite (Yes, B-body. I don't have D2D adapter in an A-body right now) - which barely gets driven - and have since blown up two HEI modules. Both have been complete failures following otherwise normal operation. Once was within 5 minutes of a cold start while running, the other was about 30 minutes after moving the car from one driveway spot to another on a cold start. South Florida weather ensures that none of this ever takes place at less than 55 degrees Fahrenheit (at worst).

I've been mulling over the possible causes of failure, I'm starting to suspect that either the Designed2Drive plate as it is now isn't an ample enough heatsink - or the placement outside the distributor behind the block accelerates the failure.

Consider the setup: It's a 360 LA running a standard Mopar electronic ignition distributor, a 4-pin HEI module with no inline resistor, Ford TFI e-core coil (FD478), and a modern voltage regulator fed by a later squareback alternator. The car did not have a tach in it when it the HEI module failed at first, but it currently has an original tach in it now, fitted with a Real Time Engineering solid-state PCB in place of the original.

The electronic voltage regulator presumably prevents the system from exceeding 12V, so I shouldn't think it failed from overvoltage. Far as I know, the TFI e-core coil's primary resistance is low enough to work properly with the HEI module (and deliver its benefits).

The first HEI module was an aftermarket unit, and I chalked up its failure as a Chinese piece of crap. However, the second one that failed was an original GM unit - marked with the logo and all - and it couldn't have been under the hood for 200 miles before this failure. Both were put down with proper heatsink compound.

I have my doubts that the tach could have caused it, seeing as it wasn't there during the first module failure.

At any rate, I'm wary of that plate at this point. Curious to hear your thoughts. I'm considering shoving one under the dash instead with a larger heatsink (and maybe a fan), but for the amount of time this thing sees the road, I doubt if I'll have much to report for a long while.

-Kurt