On 17 Apr 2004 20:28:34 -0700, (R. Wubben) wrote:

While taking my new to me'62 Cessna 172 with an O-300 (with about 75
hours on it SMOH with Millenium cylinders), I decided to start leaning
as I should on my last flight.
During the next preflight I noticed a whitish soot around the exhaust
and on the cowl just adjacent to the stack during the preflight.
Looking up on r.a.o for "white exhaust soot" I came across posts from
several years ago about the white soot being a side effect of leaning.

Does this sound right?
Am I leaning too much? (I'm still trying to figure out the lean and
rich of peak thing, especially for this particular airplane that I
have about 18 hours in).

Thanks,
Ryan Wubben
Madison, WI

one of the beautiful things about classical Avgas is that you can get
an after flight appraisal of the engine. the burning of the tetraethyl
lead is what gives the coloured exhaust.
black is running rich
mid grey is burning perfect
lighter grey through to white is burning lean.

on my little Continental O-200 I just lean to peak revs on the tacho
and I get a beautiful mid grey exhaust.
if you climb or descend by more than a thousand ft then check the
mixture again.

works for me
Stealth Pilot
Australia