I didn't have a soot level to fuel mixture ratio chart handy, so I figured I'd explain that soot is normal.
This is obvious:
Idles like crap, stumbles, heavy, visible soot out the pipe.
Not sure what 'wet looking' means. Water is the byproduct of combustion, so a wet exhaust means nothing. By 'gray' I guess you mean water vapor?
Tailpipes are full of soot. I've yet to know of a car that has a 'clean' exhaust... properly running or not. So by just looking at the tailpipe you cannot make an informed decision about the mixture of the carb. If you have devised some method (a certain mg/cm2 ratio? use a micrometer to measure the layer or soot?) please do share. I guess a good guide would be: if your exhaust looks like is out of a diesel engine then you might have a problem
Its all easily diagnosable by simply pulling a spark plug. That's the only sure way to tell whats going on with the mixture (short of an exhaust gas analyzer).
