Enlighten me about spark plugs

[John Schubert]

Scott, very true. Using the recommended plug should work every time unless there are any of the other issues evxident. I will make one additional comment, the newer Champion plugs with the siffix "C" for copper, don’t work nearly as well as the ones with the suffix "J". I found that the NGK plugs recommended for replacement of the J 6 J work very well.

[garry-in-michigan]

In the "good old daze" of sloppy sand castings, loose tolerances, and poorly refined fuels & lubricants, the recommended spark plug was only a sugestion. Some of our apposed cylinder antiques ran best with a different heat range plug in one cylinder. Many were damaged by over advancing the magneto. Things improved with better aluminum alloys and the uniformity of die casting. Even so, some of the Johnson "HD" and "TD" models had vapor lock problems in hot weather. The third port on these mounts the carburetor right next to the exhaust manifold.

The designated "J" Champion sparkplug had the side electrode end over the center of the center electrode. This was said to give a more "open" spark for better ignition in two cycle engines. I always file my new plugs back like that. I figure it can’t hurt. For one thing the way electrons gather on a flat surface makes it easier to jump from a sharp edge. For another thing, the edge gets hotter and wears down faster. A worn sparkplug will always have rounded edges. A little filing there can extend it’s life.

. . . . . 😉

[The Boat House]

[chris-p]

I too love to collect nice original plugs Tubs.

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