leaning in climb

Actually, on most of the lycomings it's not necessary to screw with this
at all. Set the best power during your run up (at your magcheck rpm).
Climb at Wide Open Throttle. WOT lready adds extra fuel to maintain
engine cooling.

Some of Lyc's specifications result in really rich running
engines. We have a 182RG that has an HA-4 carb, and it runs very rich
at most power settings when the mixture is full forward. The Precision
Aeromotive guys (former Marvel Schebler) tell me that this is the way
Lycoming specified the carb when they designed that particular engine
model (O-540J3C5D), and that you have to get used to playing with the
mixture much more than you did with a 172. We lean while idling on the
ground, full rich for takeoff unless above 3000' DA (as per POH), and
you have to lean it in the climb if you want it to run smoothly and not
smoke. When carb heat is applied in the circuit, it gets pretty rough
unless it's leaned again.
Our airport is at 2975' ASL. We get lots of leaning practice.
Dan

Thomas Borchert wrote:
Jay,

to an
over-lean condition

Wazzat?

That would be if the engine is backfiring ;-)


Personally, I simply lean a fixed-pitch prop Lyc to find peak rpm and
have never had any performance or maintenance issues in nearly a decade
of flying. The engine always seems happy and I suspect that at peak
rpm, I'm probably still blowing a significant amount of unburned fuel
out the exhaust pipe. In those planes I've flown that were equipped
with cht guage, the temps never climbed high enough to be worrisome
either.

On Tue, 15 Nov 2005 13:02:57 GMT, "Matt" wrote:

Hi everyone. I have a leaning question. The POH for my 152 says that the
mixture should be leaned to best power after passing 3000 feet in the climb.
However in other places in the POH (and the Lycoming site) they say not to
lean when at 75% power or higher in cruise. My question: Is the engine
developing less than 75% power during the climb; and is this why leaning in
the climb is OK? Does this guidance in the POH seem contradictory to anyone
except me?

Thanks for all your help.

Matt


I don't think anybody has mentioned the following information, from
Lycoming, which may be useful:
http://www.lycoming.textron.com/supp...ns/SI1094D.pdf

wrote:

Personally, I simply lean a fixed-pitch prop Lyc to find peak rpm and
have never had any performance or maintenance issues in nearly a decade
of flying. The engine always seems happy and I suspect that at peak
rpm, I'm probably still blowing a significant amount of unburned fuel
out the exhaust pipe. In those planes I've flown that were equipped
with cht guage, the temps never climbed high enough to be worrisome
either.

Here's a chart:

http://www.swaircraftappraisals.com/MeyersForum/Engine%20Info/Engine%20Operation/Pelican's%20Perch%20Mixture%20Magic_files/pp18d.jpg

The horizontal axis is leaning (left is leaner, right is richer). The
highest point of the BHP curve is peak power -- notice how close it is
horizontally to the highest point of the CHT curve, which represents
the hottest your engine gets.


All the best,


David