Heat Range (of spark plugs)
A
spark plug is designed to operate at a temperature high enough to prevent the formation of carbon deposits but not high enough to cause pre-ignition, that is, the hot end igniting the fuel mixture before the timed spark can. The requirement for different designs of engine varies and plug manufacturers provide a range of plugs for any size and reach, having suitable heat characteristics for any application. By design difference, chiefly in the length of the path for heat conduction from the central electrode to the body of the plug, spark plugs vary in degree from "hot" to "cold".
