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Conference vmszoo::rc

Title:Welcome To The Radio Control Conference
Notice:dir's in 11, who's who in 4, sales in 6, auctions 19
Moderator:VMSSG::FRIEDRICHS
Created:Tue Jan 13 1987
Last Modified:Thu Jun 05 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:1706
Total number of notes:27193

314.0. "LEAN ENGINES??" by SPKALI::THOMAS () Wed Sep 16 1987 07:59

    
    
    	In some recent notes there has been talk of lean runs. There
    is no excuse for this and there is a way to assure yourself that
    your engine isn't to lean. It's used on most pattern birds. Also
    it is done every flight.
    
    	To start richen the engine to four cycle. Now lean to what you
    think is top RPM's. Once your there gently squeeze the fuel intake
    tube to the carb. You must see a slight increase. If no increase
    is seen then your usually to rich. If there is an increase and your
    engine is to lean the engine will stop. If there is an increase
    and the engine still runs your in business.
    
    					Tom
    
    I must stress that it's a gentle pressure. Your trying to restrict
    about 5% of the fuel flow.
T.RTitleUserPersonal
Name		DateLines
314.1how long?BZERKR::DUFRESNEVAX Killer - You make 'em, I break 'emWed Sep 16 1987 10:277
    Dumb question: How long should I squeeze ?? 
    
    I guess is RPM increases, I have my answer...If it stops, again
    I have an answer.. How long does it take before I see an effect
    ??
    
    md
314.2SPKALI::THOMASWed Sep 16 1987 13:585
    
    	You should see an almost immediate increase in engine RPM's.
    
    						Tom
314.3A comment and a question...LEDS::ZAYASTue Sep 22 1987 13:279
    
    	Tom, I think your scheme will work great if the centerline of
    the tank is lined up with the center of the carb (i.e., a proper
    installation).  If the tank is installed lower, I think you'll run
    into problems.
    
    	BTW, does your trick work if you have a pump installed as well?

    	Thanks.
314.4SPKALI::THOMASWed Sep 23 1987 08:084
    It works regardless of tank location and with or without a pump.
    
    
    						Tom
314.5Beware of the hot weatherLEDS::HUGHESDave Hughes (LEDS::HUGHES) NKS-1/E3 291-7214Tue Jun 14 1988 16:0736
    I was looking for a note to put this comment in, and this is
    the best one I could find, as far as the title of the topic goes.
    
    Yesterday was the first real HOT day of the summer for us - in
    the 90s and pretty humid. Hot, humid air is thinner than cool
    air, and that effects not only the lift (harder to take off) but
    the engine performance and tuning. Several of us fly at lunch time
    at CMRCM in Westboro, but that's the hottest part of the day.
    
    My O.S. 45 FSR has been running great, and I almost never need to make
    a needle valve adjustment. Yesterday, it started up fine, sounded good,
    I held the nose of the plane up at full throttle and it leaned out
    slightly (ran a little faster) but seemed to be fine. Just the way I've
    always done things. The plane (Sig Kavalier) flew fine, but at the end
    of my 3rd flight I noticed a darkening of the oil dripping out of the
    exhaust pipe. It was an aluminum slurry, indicating some serious wear 
    going on. 
    
    Our conclusion is that it was running too lean. It wasn't real hot,
    and turned over easily (no seizing). Since it was my last flight
    for the day, I turned the needle valve a few clicks rich and went
    home. Today, I ran the first flight real rich - almost couldn't
    take off due to 4-stroking, but it leaned out when it got up. I
    ran the next couple flights slightly leaner and it ran fine with
    no more indications of wear. Hopefully, the damage was minimum since
    I noticed it right away.
    
    The moral, I guess, is to be careful of the weather, and run a
    little rich on hot humid days. Has anybody else had a similar
    experience? Oh, additional data for you analytical-types:
    Fuel - Red Max 12% nitro, synthetic oil. Ran the same glow plug
    both days. Prop - 10x6.5, same prop I've been running for 2 years
    on the plane (yes, the SAME prop). No other indications of problems, 
    started easily, etc.
    
    Dave Hughes