The idea is in fact to lean aggressively on the ground. I lean mine till
it stumbles then turn the vernier in just till it is smooth. That works
out to pretty close to idle cutoff. Leaning this aggressively, the engine
will quit if you advance the throttle, making it impossible to take off
with it still leaned.

Bob Fry wrote:

(Rick Durden) writes:

It doesn't hurt
to lean it when taxiing as well, but do so very aggressively, so that
if you forget to go to full rich before takeoff it will quit on you
rather than make a takeoff with the mixture other than at full rich.

Rick, I had a talk with my mechanic a couple of months ago about
leaning when idling. He says for my carburator and C-90 engine, and I
suppose many other aircraft engines, leaning at idle doesn't do
anything unless it is nearly at idle cutoff. It is only when the RPMs
are well above idle that the mixture control begins to really control.
So does leaning on the ground--during idle--do anything unless it is
leaned nearly to idle cutoff?

--
--Ray Andraka, P.E.
President, the Andraka Consulting Group, Inc.
401/884-7930 Fax 401/884-7950
email
http://www.andraka.com

"They that give up essential liberty to obtain a little
temporary safety deserve neither liberty nor safety."
-Benjamin Franklin, 1759