Spark Plugs - Heat Range
2005 Tundra/Skandic/Expedition snowmobiles
The proper operating temperature or heat range of the spark plugs is determined by the spark plug ability to dissipate the heat generated by combustion.
The longer the heat path between the electrode tip to the plug shell, the hotter the spark plug operating temperature will be - and inversely, the shorter the heat path, the colder the operating temperature will be.
A cold type plug has a relatively short insulator nose and transfers heat very rapidly into the cylinder head.
Such a plug is used in heavy duty or continuous high speed operation to avoid overheating.
The hot type plug has a longer insulator nose and transfers heat more slowly away from its firing end. It runs hotter and burns off combustion deposits which might tend to foul the plug during prolonged idle or low speed operation.
CAUTION: Severe engine damage might occur if a wrong heat range plug is used.
A too hot plug will result in overheating and pre-ignition, etc.
A too cold plug will result in fouling (shorting the spark plug) or may create carbon build up which can heat up red-hot and cause pre-ignition or detonation.
Updated on: Friday, December 18, 2020