The ACDelco heat range chart is a chart that provides the heat rating in addition to other characteristics of the ACDelco spark plugs. The heat rating indicates the thermal characteristic of the spark plug, or how hot or how cold the spark plug is.
The chart details the plug identification table. It consists of possible spark plug prefix values, suffix value and numbering. The numbering section consists of the thread size and the heat range. In addition to the heat rating and thread size, the chart provides the construction shape, the taper seat types, the projected gap types and the plug type. In addition, it details the resistor, the spark gap and other design features all in a single chart.
The heat rating number describes whether the spark plug has a tendency to heat up easily or whether it has the capacity to provide resistance to heating up. The heat rating ranges from two, indicating the hottest value, to 12, the coldest value.
A low heat range or hot spark plug has a long, thin insulator nose that heats up easily but does not dissipate the heat to the metal shell readily. Alternatively, a high heat range or cold spark plug has a short, thick insulator nose that dissipates heat very easily.