---------------------------------------------------------- LycomingEngines-List Digest Archive --- Total Messages Posted Mon 06/02/08: 3 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 07:05 AM - Re: Which Way to Turn Mixture Adjustment Screw on Carburetor? (manuel weber) 2. 08:00 AM - Re: Forced landing (manuel weber) 3. 04:14 PM - Re: Which Way to Turn Mixture Adjustment Screw on Carbu... (JFLEISC@AOL.COM) ________________________________ Message 1 _____________________________________ Time: 07:05:33 AM PST US From: manuel weber Subject: Re: LycomingEngines-List: Which Way to Turn Mixture Adjustment Screw on Carburetor? If you understand that the engine is running too rich, then turning the screw one way or another until it is running leaner shouldn't be a problem for you. There are no notches involved with this setting either. Screwing it clockwise will lean the idle mixture.....counterclockwise is idle mixture richer. Please understand that this is the idle circuit only. This screw has nothing to do with the primary jet. If this adjustment does not cure your rich idle condition, then there could be other problems ie float settings, carb internal air/fuel leakage...etc. I believe that all MA-4-5's also have a power valve that is activated by the throttle shaft and also has an adjustment that is set during overhaul of the carb, and set according to a chart using the carb 10 dash number. If this carb was not originally installed on your model of engine, then you may have to do some research to verify that this power valve setting is correct for your engine. This setting affects mixture ratios other than at idle. Make sure the engine is warmed up before making the idle mixture setting. Best to accomplish while the engine is running for best results. BE CAREFUL AROUND TURNING PROPELLER. You will most certainly need to re-adjust your idle speed setting after this adjustment. Manny A&P r falstad wrote: Folks, I have a Marvel Schebler MA-4-5 carb on my O-360-A1A in my GlaStar. It is running too rich. The Marvel Schebler overhaul manual for the carb doesn't say which way to turn the mixture adjustment screw (I think the manual refers to it as the air screw). The Lycoming direct drive overhaul manual tells how to adjust the mixture setting in section nine but it only says to turn the mixture screw the way you need to turn it to enrichen or lean the mixture -- it doesn't say which direction is which. Since the adjustments are so fine (one or two notches), I'd like to know which way to go before I start turning it. Can anybody tell me which way to go? Thanks. Best regards, Bob ________________________________ Message 2 _____________________________________ Time: 08:00:15 AM PST US From: manuel weber Subject: Re: LycomingEngines-List: Forced landing This may not be in the carburator. Check for a leaky primer pump, or a not fully locked and seated primer pump. If the pump is not seated, extra fuel can be introduced in the cylinders that have the primer nozzles. There is a seat in the primer pump that keeps fuel from flowing through it when not in use. Manny A&P Rv7flyer wrote: Today my 0-360 started running rough. Backfiring while at cruse. I landed to check things out. Upon restarting my engine was flooded and I had a heck of a time getting it going. Once started and cleaned out I proceeded to do a run up and noticed that I could not produce full power until i pulled the mixture back 2/3 of the way. I could not get it to idle with the mixture in all the way. The only way to get it started now is to have the mixture half way out and then lean it 2/3 of the way just to keep it running. I can produce full power at that setting. Another note I noticed that the fuel pressure continue to rise even after shutting down the engine and fuel pump. This could be from high heat in the engine compartment. I have checked the linkages and proper operation of the mixture control system. OK Carb is a MA4-5 with the f mod for the RV7A. Could i possibly be looking at a stuck needle/float valve? After it cooled a bit everything ran better. Did not have to lean as much. Any Ideas? Read this topic online here: http://forums.matronics.com/viewtopic.php?p=185676#185676 ________________________________ Message 3 _____________________________________ Time: 04:14:32 PM PST US From: JFLEISC@AOL.COM Subject: Re: LycomingEngines-List: Which Way to Turn Mixture Adjustment Screw on Carbu... Turning it right (CW) screws it in and reduces fuel flow. CCW allows more fuel. This only adjusts idle mixture however. **************Get trade secrets for amazing burgers. Watch "Cooking with Tyler Florence" on AOL Food. 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