NGK Spark Plugs are available in many heat ratings for each application. Each rating has a wide range of operating temperature. Selection on the proper heat rating is determined by the condition of the engine and the way it is driven. Wide heat range is crucial for optimum engine perfor- mance. The plug must operate at a temperature hot enough to burn off deposits which cause fouling and misfiring; yet be cool enough to prevent pre-ignition. NGKs heat range is much wider than ordinary plugs. In fact, a single NGK Spark plug type often covers the range of two or three conventional plugs. At low speeds or in stop-and-go driving, NGKs will resist build-up and avoid fouling. The same NGK plugs will also resist pre-ignition problems when severe heat is generated by high speed or heavy load condition. One secret to NGKs wider heat range rating is advanced design, materials, and construction. With the introduction of the copper core in 1958, NGK dramatically changed spark plug technology. Coppers heat conductivity and electrical properties are superior to conventional plugs. Heat is quickly dissipated from the centre electrode and insulator to avoid plug damaging hot spots and to prolong plug life. NGK also engineered a longer insulator nose to minimize carbon build-up and reduce cold operation misfiring. Superior construction. Longer life. Optimum performance. All are standard with NGK, the brand specified as the source for serious power on more new automotive, motorcycle, snowmobile, marine and small engines than any other spark plug in the world.