> -----Original Message-----
> From: Steven Newell
>
> If the black soot is easy to dust off, sounds like carbon fouling. Top
> two causes would be a too-rich fuel mixture or sustained low-speed
> operation. If your ocassional driving is generally at lower speeds
> around town, then fine black soot might be considered 'normal' even for
> a well tuned car.
Why does this happen? Is this because low-speed operation would run
off the carb's idle metering circuit, which provides a rich mixture?
(Assuming, of course, that SU carbs even _have_ an idle circuit.
They are strange beasts.)
Thanks
-Mark
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