Have a 66 chevelle with hei on it. Car had a 350 when I got it and ran fine. I put in a 327 and put the hei back on. i did have it rebuilt frist,also I put a one wire alternator on and and got rid of the voltage reg. put on a new horn relay,new junction block. Anyway after starting and breaking in cam car would not start rerplaced module and it started. But when I plugged in the tach it did it again. I cleaned up ground on tach and replaced module, it started. though i had it fixed. started and drove it several times was okay until today. I put in three modules today . frist i unplugged tach it was fine then plugged in tach fryed it next I took tach ouit of carput in module wound not start it was fryed. got another it started.let the car set for couple hours went out and it won,t start. Also my fuel gauge has not worked since I put in new tank and sender don,t know if they are related. HELP. also I have a voltage spike when the car frist starts . I do have 12volts to distributor.And checked to see if it is 12 volts with key in start postion. Any ideas would be appprecated. Thanks Duane.Also the fuel gauge is new.