sorry if this has been asked before but could not find anything helpful on this subject.
OK this pertaines to my 63 Belair with a 355
I have an HEI cap ,rotor,module,wires from accel.
ok my prob is that if I let the car sit for any amount of time 2 or more days it acts like it has lost all timing. after i get everything set up again it runs ok and then i stop it and restart after a few hours and still runs great .But if i let it set for a few days the car will not restart it begins to backfire and all hell breaks lose after that i usaully say a FEW choice words and start all over tearing apart my ignition system. pulling plugs and cleaning them off.checking all wires and all of that stuff
"that is why I bought my 1990 Iroc G92"

 

Maybe you should try replacing that Accel module with a stock one and see if the problem goes away...