how to properly lean a carb engine

[Apollo]

Okay so let me get this straight. Let me try to apply this to our 1962 M20C

1) Before takeoff do the standard runup. RPMS to whatever (15, 17, 20 whatever you prefer). Full rich mixture then lean until RPMs decrease then give it the ole right turn 3 times trick

2) Cruise. Look at EGTs. Lean mixture out until you find a PEAK or the engine runs rough again? Then do the XX LOP or ROP. Finding the peak is the scary part for me. Am I supposed to start over with full rich and then slowly find my PEAK or....?

3)  Landing. I'm in West Texas so my airport elevation is 3k. We don't ever push the mixture in before landing. But, what about if I fly to Houston, do I push the mixture in full rich?

 

 

Thanks everybody

[Shadrach]

Quote: Apollo

Okay so let me get this straight. Let me try to apply this to our 1962 M20C

1) Before takeoff do the standard runup. RPMS to whatever (15, 17, 20 whatever you prefer). Full rich mixture then lean until RPMs decrease then give it the ole right turn 3 times trick.

Hell no! Take off full rich unless DAs are above 3K and even then only if you need max power. I lean in the summer at a 700ftAGL 1800ft turf strip when the DA is~3000ft. I lean for typical take-off target EGT on the leanest cyl, for me that's #3 and I shoot for about 1225df WOT.

2) Cruise. Look at EGTs. Lean mixture out until you find a PEAK or the engine runs rough again? Then do the XX LOP or ROP. Finding the peak is the scary part for me. Am I supposed to start over with full rich and then slowly find my PEAK or....?

When setting ROP use leanest cylinder as a ref, when LOP use richest cyl as a ref. If I were you, I'd just lean until rough and enrichen to smooth and be done with it.

3)  Landing. I'm in West Texas so my airport elevation is 3k. We don't ever push the mixture in before landing. But, what about if I fly to Houston, do I push the mixture in full rich?

I don't, I enrichen a bit in the descent to keep the EGT cool. This set's me up for a max power go around, which I hope I'll never need...

 

Thanks everybody

[Hank]

In my C, I do runups "by the book." That's 1700 RPM, test the prop, test the mags, check the suction.

For Takeoff, everything goes forward. For the occasional high DA, at the end of the runway, stand on the brakes, push everything forward, lean for peak RPM, enrichen slightly and go.

Sometimes I remember to lean during the climb using Target EGT, but I need to redo a Standard Day Takeoff and make firm note of the EGT reading. Your EGT reading won't work for any other plane but yours, and if you replace the sensor or install an EI system, the numbers will change anyway. Values don't mean much, what counts is the position/distance relative to peak.

For descent from cruise, I just establish 500 fpm, trim out the forces, and don't touch the power levers. As I come down, MP and EGT both rise, so I move Throttle [back] and Mixture [rich] to maintain the cruise values on both. Recovers some of the high fuel burn/slow ground speed from the climb.

Prior to pattern entry, I'm usually at reduced throttle [18-20"], and go to Full Rich; the final deceleration usually requires less throttle [~15"] and level altitude. Flaps go down whenever I reach the white arc, followed by gear. But I think your gear speed is higher; mine is Flaps at 125 mph, gear at 120 mph. Prop forward no later than gear down.

[Hank]

Quote: Hank

Sometime soon I plan to make the normal weekend run one way at 23/2300 and back at 22/2400 [almost always at 3000 msl] and see if there is any difference. I'll record IAS, GS and actual fuel burn at the pump [one tank each way, usually 8 gals roundtrip]. Leaning will be the same-old same-old. If the rain holds off, maybe this weekend?