Heat Ranges

HEAT RANGE
Heat range of a spark plug can and does require changing due to weather conditions.
Choosing the correct heat range is a bit of a black art – the optimum plug tip temperature should be not less than 450 degrees Celsius to max 870º degrees Celsius.
Outside of this window it is considered to be an incorrect heat range.

PLUG TOO COLD
Plug temperature remains too low and causes unburnt fuel to deposit at the firing end, this causes electrical leakage path and subsequent plug failure.

PLUG TOO HOT
Plug temperature rises too high and induces abnormal combustion, this leads to meltdown of plug electrode as well as piston damage.
The Zap Spark Plug Tester is not going to give you all the answers but I know it will steer you in the right direction without all the other frustrations facing the racers and their mechanics.
There is one thing that I have always recommended:

“Don’t ever fit a spark plug into your engine, whether it is new or used without testing it in the Zap Spark Plug Tester”.