The standard OE carbon brush in GM's HEI in-cap coil distributor has a very high (5k to 10k Ohms) resistance. When an aftermarket capacitive discharge ignition system, such as an ACCEL, Mallory, Crane, Holley or MSD unit is installed, this high resistance can create enough heat to melt the distributor cap. ACCEL's low Ohm contact brush solves this problem because it passes virtually all the energy to the rotor without causing excessive heat build up.
