weak spak

As far as different plugs, anything which heat insulates the plug somewhat from the head or block causes them to run hotter, as the heat sinking (heat transfer) to the relativley cooler head or block (versus the combustion chamber) is less effective. On plugs that use a washer, I have seen guys add an extra washer to accomplish that. A hotter running plug may be better able to burn off potential fouling deposits such as excess fuel or oil. If those tractors were used as they were designed for i.e. long hard full loads at open throttle with high engine temps, plug fouling wouldnt be as much a problem as our no load parades and idling n puttering around lol.

John T

On Magneto Ignitions, use wire core and NOT carbon core suppressor type plug wires.

Its critical on mags to have good clean points gapped correct, the CORRECT size of any condensors, and good caps n rotors etc.

If the plugs are fouling and when removed have a flat black colored sooty appearance, thats indicative of excess unburned fuel from,,,,, running the carb too rich,,,,, ,,,,air inlet restrictions in the air cleaner or piping,,,,, ,,,,chokes not staying full OPEN,,,,, ,,,engine not running hot enough,,,,, ,,,too cold heat range plugs,,,,, ,,oil burner or low compression,,,,, ,weak spark

It can help if you use shutters or t stats or radiator air restrictions TO KEEP THE ENGINE TEMP UP OVER 180.

It can help to use plugs that are rated HOTTER then specified.

It can help to avoid long idle periods and run the engine/carb on the lean side.

OF COURSE, as you speak of, IT HELPS TO HAVE A GOOD HOT BLUE SPARK.

"Thats all I have to say about that" (and about all I know lol)

John T, retired electrical engineer in Indiana