Spark Plug: Description and Operation

Spark Plug Construction:

Spark plugs provide a path for the high secondary circuit current to flow to ground. Current reaches ground by jumping the gap between spark plug center and ground electrodes. The spark created, when current jumps the gap, ignites the air/fuel mixture.

The temperature of the spark plug is determined by the length of the insulator and the size of the heatsink area. The center electrode temperature ranges from a low of 392°F (200°C) at 10 m.p.h. to a high of 1472°F (800°C) at 80 m.p.h.