I have a 83z and built a 383 for it. It was a Calif. model and I took everything off the engine and dropped the motor in. There is nothing stock on the motor including the computer driven spark advance. I used a Accel Performance HEI Distributor in it. Here is the problem....
I am now on my 4 distributor. It works fine for about 2 hours of run time then all spark goes away. When it is working, the tach reads over double. Keep in mind, it is the factory tach and wiring. This time I replaced the spark module and it started right up. When it dies, it backfires and shuts down. Any suggestions?

PS.. I know and have ordered an MSD system.

Mike

 

So the backfire and engine stopping is classic symptom of losing all spark. I'll bet you are overheating your spark module. Not sure why.