70 dart 470 ci drag car build.

MMT isn't known for keeping plugs clean, it can be a little harsh on them.
Yeah we ran into that on my engine last year but it was running so clean at 1 to 1 linkage. There was absolutely 0 orange this time and just a little grey , porcelain was white basically a perfect plug too me and it was reading rich, so I don't know what to think.