C172 Engine Question
 

What is the best way of adjusting the fuel/air mixture?

Well for just adjusting it, you should do it slowly, avoid abrupt reductions (i.e. don't pull the mixture straight to half-way out, in flight.)

If your asking on how to best lean it, it all depends on what type of performance you want, best range or best endurance.

Anyway, the best place to find the most accurate/correct way to do it is in the Cessna 172 P.O.H. it should explain how to properly lean for both taxi and flight, and what you want the engine instruments to be reading for the type of performance you want.

NE Pilot is dead on. Also, if the aircraft has a modified engine (i.e. not original or upgraded, etc), you can also check the engine manual (from the engine manufacturer).

What part of the poh explains that I can't seem to find it.

Everything you need to know about leaning can be found in the normal procedures section of the Cessna 172 POH (section 4).

Thanks Alex, now my question is it recommended to lean at full power settings? Or do I have to reach my cruising altitude before leaning the mixture? How do you guys do it?

The "best way" will also be determined by the aircraft having an Exhaust Gas Temp (EGT) guage. If you have one of these, you'll be able to lean much more precisely. If not, you're limited to using the old "lean until you get a rise in RPM and make it slightly rich from there" method.

Also, don't pull on the mixture, unscrew it. When it comes time to go full rich again, you can push in.

Normally, you'll lean after reaching cruise and setting cruise power. Now, if you're at a high altitude airport on a hot day (=high density altitude) it may be nesessary to lean for best power before taking off.

Since we are on the subject, isn't it true that with Carberuator equipped engines, using a EGT gauge to lean the mixture is much less accurate than fuel-injected engines since fuel injection systems distribute a much more precise and equal amount of fuel into each cylinder?

Therfor, some cylinders could be hotter than others in a carberuater equipped engine... Sorry its late

I believe the for the 172 it is reccomended not to lean in a climb below 3,000', many people confuse this with not leaning below 3,000'. If you are climbing higher than 3,000' it is reccomended to lean, after passing through 3,000'.

But remember, anytime you make a power change you should adjust the mixture, for the new power setting. The method I know (and this will help in complex aircraft) is if you are going to increase power, you rise from the right, meaning adjust mixture first, then prop (if you have it), then throttle, and you lower from the left if you aree decreasing power, adjusting throttle first.