How to configure engine power 55%, 65%, 75% on Piper Archer / Piper Cherokee

Most pilots, even CFIs, don't understand how to properly configure engine for various altitudes on a simple Piper Archer. The advice of "full rich below 3000" is simply wrong. Below is a simplified procedure based on the POH.

It will ensure better performance, longer range, and longer engine life.

The advice of "lean until running rough, then add some" is better, but still imprecise. 

First, see POH section 4.27 CRUISING on how to configure engine.

Simplified procedures

Climb

1. Mixture, throttle full forward
2. Note the EGT temperature just after takeoff
3. As you climb EGT will drop (too rich). Every 500 or 1000', lean mixture slightly to raise EGT back to the temperature you noted on takeoff. DO NOT allow temperature to get higher than this!
4. At 6000' lean much more to get peak EGT. Note the temperature.
5. Every 600 or 1000' above 6000' are-lean mixture to get back to peak EGT.

Best Power Cruise (fly fast):

1. Mixture, throttle full forward
2. If < 6000', reduce throttle to achieve RPM setting in table below -35 RPM
3. Lean mixture to peak EGT

Economy cruise

1. Mixture, throttle full forward
2. Reduce mixture to get desired RPM in table below

On descent

1. Keep engine lean
2. As you descent, engine will start to run rough (too lean). Enrichen mixture just enough to make it run not rough.
3. Don't forget GUMPS at the FAF!

I made a table from this chart showing RPM settings at standard temperature for the RPM settings to get 75% power. DO NOT USE HIGHER RPM than this table or you will damage engine.

(65% and 55% are left as exercise for reader to fill in)

Pressure alt. 15c	RPM for 75% power	For 65%	For 55%
0	2480
1000
2000	2540
3000
4000	2570
5000
6000	2630
7000
8000	2670

If it's warmer than standard, air is thinner, therefore engine produces less power, so you can use higher RPM setting. If it's colder than standard outside, air is more dense, so you must use lower RPM setting. You can expand this table for different temperatures and also for 65% and 55% settings.

For example if you're going to level at 4000 and cruise at 75% power you'd do this:

1. Mixture, throttle full forward
2. Lean mixture until you get 2570 RPM