Local color. local color-The true color of an object or a surface as seen in typical daylight, rather than its color as seen through atmosphere or interpreted by the taste or imagination of the artist. Thus the characteristic local color of a lemon is yellow.
A spark plugs reach is calculated by the length of the threads. It is measured from the seat of the plug to the end of the threads. It should be noted that the reach does not include the electrodes, or an extended metal shell. When custom-selecting a spark plug, the electrode length and projection should be included in the calculation when taking into consideration the clearance in the combustion chamber.
A spark plug is said to be hot if it is a better heat insulator, keeping more heat in the tip of the spark plug. A spark plug is said to be cold if it can conduct more heat out of the spark plug tip and lower the tip's temperature. Whether a spark plug is hot or cold is known as the heat range of the spark plug.