Carbon on porcelin of plugs,flathead V8

[Tinker]

I'm guessing you mean on the engine side. Short runs will build up more so, then when you are running it up to temp. Fouling is usually a rich mix. Best is a brown plug but to be honest I don't ever see one. But if it never leaves the driveway, that won't help. I'm not bashing, as I don't run around the country putting 1ks on my flatheads every week.