Spark Plugs

SPARK PLUGS





Timed pulses of 10,000 - 20,000 volts from the ignition coil arc between the spark plug electrodes to ignite the fuel/air mixture near the end of each compression stroke.

Spark plug electrodes are subject to high temperature stresses since chamber temperature can vary from 5400°F. during combustion to only 140°F. during each intake stroke.

Even with the development of temperature resistant alloys, the sharp corners of the electrodes will erode with use; the gap between the two electrodes will also increase. Both of these tendencies increase the amount of voltage required to jump the air gap - eventually the plug will not spark.

With today's extended maintenance intervals, cleaning and re-gapping used plugs during a normal engine tune-up has become an obsolete procedure. Spark plug shop work consists of checking that the plug number is correct for the car, gapping the new plugs, and torquing them correctly in the cylinder head.