Varies with the engine, with the fuel atomizaion scheme, displacement,
etc, but most of us live with a 15:1 air fuel ratio as a starting
point.

Jim




On Mon, 14 May 2012 23:58:14 +0000, dtvonly
wrote:


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.