[mfleming]

I live at an elevation of 4,000' with DA's commonly at 8K or above in the Summer. We practically never ever use full-rich mixture. That stuff is for sea level dwellers. We taxi at just above ICO to avoid lead fouling. We optimize mixture at run-up and this usually results in a knuckle or more pull on the mixture knob.

Once you get fairly familiar with a specific aircraft you get very good at approximating the mixture setting for landing based on experience and seasonal temperature changes. Both prior to run-up and during descent to land.

Could you describe your process for optimizing the mixture on the ground? It also sounds like this is the mixture setting you use for takeoff.
I’m at a field elevation of 4000’+ …

 

[JonJay]

Side note on idle mixture. Many of us set our idle speed way lower than spec. I set mine for 650rpm. You can’t adjust idle mixture at that low of rpm. Bump up to 750 or 800, set idle mixture, and then set idle stop for 650. Ground lean accordingly.
As far as high DA take offs, I use either Mike Busch’s rolling adjustment whereby you lean while rolling to power loss, then enrichen to best power, or Paul Dyes run up method where you run up at 1800, lean to that, then keep mixture there for takeoff, monitoring and adjusting EGT’s accordingly.
Both work. Paul’s method is easier.

 

[Bavafa]

EGTs are my guide for mixture control and settings at take off and other phase of the trip including during climbs other than when I am taxing which is leaned more aggressively.

 

[jliltd]

Could you describe your process for optimizing the mixture on the ground? It also sounds like this is the mixture setting you use for takeoff.
I’m at a field elevation of 4000’+ …

I do something between Busch and Dye's methods. Learning to fly at high DA's here instructors have their Cessna trainer students lean at 1800 to engine stumble and then screw the mixture's vernier control in three half turns. One for you. One for Mama. And one for the babies. With the RV8 throttle quadrant I have a feel for a good place to start based on temperatures. After engine start is it located abeam the the "M", the "T" or the "E" on the "MIXTURE" placard? Depends on the day. During taxi I lean aggressively, right up to but before ICO. At run-up I still use the "engine stumble" method followed by enrichening a bit albeit without a vernier. No two aircraft are the same but here is how my current mount likes things on the takeoff roll: I watch my EGTs and make sure that they are where I know safe levels for this particular engine/airframe combination and probe locations. Those approximate EGT values for 9GW are 1300 to 1400 EGT at home high hot field and 1220 to 1350 at sea level locations. I usually don't have to adjust on the takeoff roll to keep the EGT in the mid to lower part of those areas but do on occasion adjust mixture. I always have great CHTs in this particular installation so can climb out at 65-70 knots and not have CHT issues.

I have flown an RV-6 that tended to have high CHTs and so the takeoff profile was completely dictated by CHT temps and so tended to have a shallow climb. So that was the primary attention getter with an occasional glance at the EGTs. So more workload to keep track of everything on takeoff, including EGTs.