ORIGINAL: 91zulu
How do one know the the right spark plug is in a gas engine. Now folks this don`t apply to the popular name brand engines with manufacture web sites with all engine info available, just the off brands and brands that are long gone. I think this bit of information I need to know, to be sure my engine is operating at optimum.
The insulator nose length is a determining factor in the heat range of a spark plug, the longer the insulator nose, the less heat is absorbed, and the further the heat must travel into the cylinder head. This means that the plug has a higher internal temperature, and is said to be a "Hot" plug. A hot spark plug maintains a higher internal operating temperature to burn off oil and carbon deposits, and has no relationship to spark quality or intensity. Conversely, a "Cold" spark plug has a shorter insulator nose and absorbs more combustion chamber heat. This heat travels a shorter distance, and allows the plug to operate at a lower internal temperature.