Rick Girard
LEZ + 13B

P.S. I did come across something interesting in the 152 POH about

leaning. for

maximum economy the engine is to leaned to peak RPM and continue leaning

until RPM

drops 15 to 50 RPM!  Variation is whether you have a Lyc O-235 L2C, N2C, or a
Cont. O-200. Sounds remarkably like lean of peak to me.

Peak RPM would be max power. Well rich of peak EGT.
15 to 50 RPM may still be rich of peak EGT.

Paul Lamar

Paul is right.  Max power is richer than max EGT, you are still richer than
peak EGT.

What's really going on here is pretty different than it appears at first glance.
The mixture distribution is poor enough with any of the carburated aircraft
engines that on cylinder starts to lose power slightly.  The other cylinders are
probably much richer, or at least, just the same.  A friend's
Long EZ uses an Ellison carb and it has such uniform mixture distribution that
it will run smoothly until it just starts losing RPMs.  You can lean it out, too
lean, so he has to be careful.  I have a regular carb, so use the Cessna
technique and waste fuel on 3 of 4 cylinders.

Bill Freeman
Long EZ builder & pilot
BSME, MSME
EAA Technical Counselor

 
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