I also have a Cherokee 140 and I just climb to altitude and then lean. I don't think it would be practical to try to lean while climbing. I've never had any problem with detonation which some higher performance engines might experience. You can get all kinds of advice on leaning. I have an EGT so it's practically like cheating. With no EGT though the general way is to just back off on the mixture slowly until you see the rpms start to drop off then crank back in about three twists on the mixture. Some folks say to just back off until the engine stutters then crank in three three twists. I tried that once. It worked fine, but I found it a little unnerving so I just use my EGT now. There may be better ways, but that's the best I can tell you. Happy flying.
Cathead, I see you have asked this question on another cherokee forum. There is a pretty good dialogue going on this subject on the AOPA forum. Might be worth checking out. It is of interest to me also as I have a 74 Cherokee 140 with no EGT. The consensus seems to be to lean as you go thru 5000'. Good luck.
I have to agree with you and especially during those hot months when the OAT is very warm ................... I would say if you had to use this technique I would only use it during the cooler times of the year where OAT is much lower and the airflow through the engine cowl is not as critical due to the colder air. However I could see an argument to be made for keeping the plugs from fouling with this "lean as you climb" technique. I have never considered this and probably would not ever use it until level off and cruise power adjustments made.
yes I agree with leaning after you level off, I have a 1967 140 with a 160 conversion and powerflow, also have a UBG 16 engine analizer. you want to keep your CYL. head temps below 380 degrees on climb out at 85mph it gets pretty close even at 90mph ... but I even come back on mixture (at altitude) untill engine runs rough then back untill smooth, cyl. head temps run at 340 - 350 and a nice 7.8 gph at 2450 rpm.
Leaning as you climb is quite helpful in the climb rate department. The engine gets overly rich as you climb and loses a fair amount of power from this source alone.
With no gauges lean to highest RPM or best climb rate after crossing 5,000'. This is really no different than the way one sets the engine for a high-altitude takeoff. Same problem, same solution.
With an EGT gauge lean the mixture to obtain your typical sea-level takeoff EGT every 4,000' or so.
(Both of the above assume you are climbing at full throttle, full RPM. If you've brought the power back during climbout for some reason and you're worried about rate of climb, give it more power first.)
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Mike
With no gauges lean to highest RPM or best climb rate after crossing 5,000'. This is really no different than the way one sets the engine for a high-altitude takeoff. Same problem, same solution.
With an EGT gauge lean the mixture to obtain your typical sea-level takeoff EGT every 4,000' or so.
(Both of the above assume you are climbing at full throttle, full RPM. If you've brought the power back during climbout for some reason and you're worried about rate of climb, give it more power first.)