Check out this Autolite 45. Factor in that this engine is supercharged. It is the only plug of 8 that appears this way. The other seven are evenly lightly sooted due to a fairly rich mixture and mostly easy mid-winter runs. I switched back to the 45's for the season when colder driving conditions and short hops caused the Autolite AR33's to foul on a regular basis.
I've never seen a plug sooted only on 1/2 the insulator up to a horizontal edge line. The back has a mirror image soot-limit edge line at about 180 degrees around.
I have an idea but wanted to pose a mind teaser to the rest of the forum. Also I could be totally wrong and one of the members could bring this anomily to light.
-Geary
Last edited by Aggressor; March 8th, 2012 at 08:40 PM.
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