Q12:What is the heat rating of a spark plug?

　　A： spark plug must dissipate the heat produced by the combustion gases. The heat rating is a measure of the amount of heat dissipation.

　　It is essential to use a spark plug with a heat rating that matches a specific engine and its condition of use.

　　When a wrong heat rating is selected,

　　When the heat rating is too high,

　　The spark plug temperature remains too low and causes deposits to build up on the firing end; the deposits provide an electrical leakage path that possibly cause misfire.

　　When the heat rating is too low,

　　The spark plug temperature rises too high and induces abnormal combustion(pre-ignition); this leads to melting of the spark plug electrodes that could cause problems such as piston damage.