I should mention that I only have a single EGT probe on my engine. I
keep wondering if I should get an analyzer. So much I could buy...

Regards, Ross
C-172F 180HP
KSWI


Ross Richardson wrote:
One of the things I found with my O-360 and C/S prop is that at
altitudes where the MP falls off, generally to 22" - 23", I pull the
throttle back to see a slight decrease in the MP. Then I lean. I find I
get better fuel burn results and very near the Lycoming manual for this
engine. Leaving the throttle in full at high altitudes, tends to burn
more fuel and I am not sure I am getting anything out of it.

Comments?

Regards, Ross
C-172F 180HP
KSWI


Frank Stutzman wrote:

Doug wrote:


I think the main thing is to lean enough to get proper burn, but don't
lean so much as to burn things up. I have some friends with probes on
all cylinders and carbureted engines who have tried to run lean of peak
and they have mostly given up. Just doesn't work on carbureted engines.



If you said "most" carbed engines, I probably wouldn't quibble. However,
it does work on some. It certainly works on my Continental E-225 with
a Bendix PS-5C carb. Its harder to do, but can be done and does
work. Here is what I had to do:

1) overhauled my carb and had it flow tested to make sure its doing
its job.
2) Pull off the throttle back a bit less than one inch. This put the
carb out of the enrichment mode that it is with full throttle. I
think it may also put a bit of turbulence into the airflow that helps
the fuel vaporization.
3) If I can't get smooth LOP operations with the above, I'll play a
bit with carb heat (which is actually alternate air on my plane).
Causing the induction air to be a few degrees warmer will often help
get the vaporization (and hence good distribution) needed.

I believe I've heard the GAMI folks say that getting good distribution is
easiest on the large Continentals. Something to do with the way
the stock induction is done.

-- Frank Stutzman
Bonanza N494B "Hula Girl"
Hood River, OR