Soot is due to an over-rich condition. Oil fouling is black and wet. It sounds like the power piston in the carb is stuck in the down position, which keeps the power valve open all the time. That allows fuel to bypass the main jet and the mixture stays in the full-rich range. The power piston should move freely up and down, and as soon as the engine starts, the piston will lift from manifold vacuum and allow the ball check valve to close and route the fuel through the jet only.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
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