Seen that a few times before, the carbon tip in the dist. cap drops out as the cap is installed and sits sideways, burns the rotor and quite often the dist. cap as well. Removing the ballast resistor gives more primary voltage to the coil allowing it to give more spark if needed. When the carbon tip is missing it will put out more voltage to jump the extra gap. ( remember the coil is lazy, it will only put out what is needed ) By applying full 12v and not 6-8v as is normal when the ballast is in the circuit the coil can put out much more than the 22,000v, this is what a standard coils max. put out is. The coil won't last too long as it starts to break down inside, heats up the cooling oil and pops the top and spills out the oil.
These earlier ignition systems usually ran on about 8-14,000v for normal driving and went up to 18-20,000v under load or hard acceleration.
If you are using a 4 prong ballast instead of a 2 prong it might be reducing the available voltage on the primary side of the coil even lower than 6v.
