Spark Plug Gap

Anonymous-0 · Feb 25, 2011

I have a hotter than stock magneto in my tractor. Is it OK to increase the spark plug gap a little to help prevent plug fouling?

Jon Hagen · Feb 25, 2011

Yes, within the limits of the magneto and plug wire insulation.

Anonymous-0 · Feb 25, 2011

Jon Hagen: Thank you for the reply regarding spark plug gap.

NCWayne · Feb 25, 2011

I've been reading an old manual from the late 30's/early 40's about the ignition system and how it works. It's amazing the information provided in a really clear, consise manner. That said increasing the plug gap does nothing to prevent fouling, in fact increasing the gap beyind spec actually changes the timing somewhat, believe it or not. The fouling of a plug is more a product of how "hot" the plug is. That is determined by the length of the insulator nose which in turn determines how much heat the electrode retains in order to stay hot enough to burn the carbon deposits off and prevent fouling. Below is a link to NGK's site that gives you all this information about how a plug works and then some. Hope this answers your question. Good luck.
Plugs explained

buickanddeere · Feb 26, 2011

Run the coolant at 195F. Lean the mixture out at idle and at power. Work the engine and operate at higher rpms instead of just putting around
You haven't stated the application but either a non resistor plug such as an Autolite 3116, 216 or 437 will fit.
The fouling will go away unless the engine is a gross oil burner.

MarkB_MI · Feb 27, 2011

Increasing spark gap increases the voltage at the plug. The dielectric strength of the insulation of in your magneto and on your wires will dictate how much voltage the system can handle. So you're pretty much limited to the stock plug gap.

Spark Plug Gap

Anonymous-0

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Jon Hagen

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Anonymous-0

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NCWayne

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