"dtvonly" wrote in message ...


Hi. I am a student pilot and have always done "proper" leaning per
flight altitude. I should have asked this a long time ago
but...anyway...when using the mixture control to get "optimum" RPM at
altitude, what is the "optimum" air/fuel ratio ? 3:1, 4:1, etc...
Thank you.
dtvonly

Unless you have a device that reads out your air/fuel ratio you should
probably just use the old method. At cruise altitude with power/speed
stable, just lean out the mixture control until the engine runs a little
rough and then push it back in about an inch.