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rotorwrench · 10-14-2019, 06:31 PM

Heat range is mostly about how fast a plug dissipates heat. The faster it does that then the colder the plug is. It is controlled by the design of the ceramic insulator that is inside the combustion chamber. The more insulation, the smaller the space is between the insulator and the inner barrel of the threaded portion of the plug.

A hotter plug will have more space in there and less insulator around the electrode. The hotter plug heats up faster and will burn out more combustion bi-products than a colder plug will. If a plug fouls more than it should, a hotter plug would be in order to decrease fouling. The problem is, I don't know if there are any hotter ones made in this day and age. A person has to find an old Champion 30 or 31 set that still works or live with what they have.

10-14-2019, 06:31 PM	#17
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,440	Re: Model T Sparkplugs Heat range is mostly about how fast a plug dissipates heat. The faster it does that then the colder the plug is. It is controlled by the design of the ceramic insulator that is inside the combustion chamber. The more insulation, the smaller the space is between the insulator and the inner barrel of the threaded portion of the plug. A hotter plug will have more space in there and less insulator around the electrode. The hotter plug heats up faster and will burn out more combustion bi-products than a colder plug will. If a plug fouls more than it should, a hotter plug would be in order to decrease fouling. The problem is, I don't know if there are any hotter ones made in this day and age. A person has to find an old Champion 30 or 31 set that still works or live with what they have. Last edited by rotorwrench; 10-14-2019 at 06:36 PM.