When GM started using HEI's around 1975, I had a failure in a new company truck.The rotor, cap and wires were all burned. The culprit was the spark plugs,the truck went 30,000 miles on the original plugs,the electrodes were almost complety eroded away,yet the truck still ran ok.After that, I always replaced the plugs sooner ,never experiencing another problem at all. The HEI produced so much voltage to fire the worn plugs,it destroyed the wires and cap.
