The only times I had to replace a distributor cap was when they got a carbon track, cracked, or the carbon button gets damaged, almost all caps, just get dirty on the outside and need to be cleaned with some dish detergent and rinsed and wiped dry, or a hair dryer, or some compressed air to dry it out. A pocketknife will clean the aluminum contacts when they get some crude on them. When the cap gets dirty, on humid or rainy days, they can arc across the cap between contacts and cause missfires, or a carbon track across the top, bad spark plug wires (open or high resistance) can cause this also. Here's a little information on the high voltage in a system, in a working system the voltage to fire the plugs, depends, on the compression, the engine load, spark plug gap, the rotor gap to the distributor contacts for each cylinder, plus more. For instance, let's say an engine idling requires 14,000 volts to fire the plugs, and your system can produce a maximum voltage of 30,000 volts, this means your reserve is 16,000 volts when idling, now you accelerate the engine, the voltage to fire the plugs increases to 22,000 volts, now your reserve is 8,000 volts, as long as you have some reserve, the engine will not miss fire for those reasons. Increasing the maximum voltage available to 40,000 volts, by changing components, makes no improvements, as far as the engine is concerned, as you don't have any demands exceeding the 30,000 volts of the stock system. So this means keeping the high voltage components clean, rotor, dist cap, ignition coil top, sparkplug insulators, spark plug wires and dist HV coil wire clean, regardless of what electrical ignition system you use, so you have a reserve voltage under all conditions. My 2 cts. Good Luck.