Spark Plug Design Symbols.pdf

This is MS-Marshal Spark Plugs Design Symbols, it explains the specific meaning of each letters of the part number. For example: F7RTC-11 F means the thread size, 7 means the heat range, R means resistor, T means projected insulator, C means the center electrode material, -11 means the ignition gap is 1.1mm. You can find the right specification from this chart. This chart is not perfect, thanks for your suggestions for improvement.