They look cold to me too, but not lean to me though. It looks like it’s rich on the transfer slots or he may be able to drop the primary main jet a couple of numbers and then open up the power valve channel restricters if it’s lean at WOT.
Many years ago, I read an NGK article, or maybe it was in the catalog or something, but it said for heat range you want 2-3 threads showing color.
Champions I don’t go much over 1 thread. The playing on the two plugs are different, but, IIRC in the end they both end up running at the same heat load. So either Champion uses a higher temp plating than NGK, or NGK uses a lower temp plating.
However that works. It’s damn sure confusing. Just looked at a set of AC plugs yesterday, and they look really nice, but I have no idea what plating they use, so I’ll use them and see what they look like.
