Multi-Ground Plugs

[sparkplugs.com]

Some combustion chamber designs, such as rotary motors, require that the spark plugs have the ground electrode placed to the side of the center electrode rather than below as on a traditional plug (see photos below.) This firing tip design tends to erode the tip of the ground electrode faster than a traditional plug, and as erosion at these points creates a larger gap between the center and ground electrodes, plug misfire will occur. Thus, by having more ground electrodes, you extend plug life. It is important to note that multi-ground does not mean multi-spark - electricity follows the path of least resistance, there will still only be one spark at a time. Therefore a multi-ground plug will not perform any better and may actually perform worse than a traditional plug, unless the engine is designed for a multiple ground plug.

[rico387]

the one on the right looks kinda like a Lycoming plug, although the electrode is kinda long (real long). The one on the left looks like the NGK's I use in my weedwhacker, edger, chainsaw. But honestly, I don't know. I can barely run a can opener.

[sparkplugs.com]

Originally Posted by rico387

the one on the right looks kinda like a Lycoming plug, although the electrode is kinda long (real long). The one on the left looks like the NGK's I use in my weedwhacker, edger, chainsaw. But honesttly, I don't know. I can barely run a can opener.

Both are NGK plugs, the one on the right a traditional single ground w/ 2.5mm center electrode.

Careful...can openers can be dangerous

[rico387]

yup. looked like NGKs anodizing. Mrs.rico387 caught me filing the contacts on her can opener and ran me out of the kitchen. I'm sure I could have made it better. BTW-we all know that Continental/Lycoming electrodes are much shorter.