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Comments below from David, Alon A-2 #A35: ========================================================= Jon Page wrote: > > Subject: Power Loss > Date: Tue, 21 Nov 2000 19:35:56 -0800 > From: Jon Page <[EMAIL PROTECTED]> > Organization: @Home Network > To: ercoupe <[email protected]> > > On most carbs the lean mixture control is not much more than a joke. > Most kill the engine dead when eased out at cruise settings. No warning > or slight increase in RPM. Comment: This is a classic case of too lean a cruise mixture that can be cured through boring out the main jet as you mention below. ======================== > I've heard numerous stories of power loss on > takeoff or at cruise. I personally have had this problem on both the > coupes I've owned. Comment: This could also be caused by an extremely lean mixture! ======================== > After much study and contemplation of the problem, I feel sure I have > come up with an answer. If you look at the air intake layout on an > Ercoupe, you will see the air is taken in about a five and a half inch > funnel that tapers down to about two inches as it nears the carb. The > power failure virtually never happens on the ground, but add > seventy-five to a hundred miles an hour more air being forced in the > intake by the plane moving through the air and you are, in effect, > supercharging the carb. This funnelled air leans down the mixture > because the main jet is only so big and can't keep up with the increased > volume of air being scooped in. A fellow couper I know solved his > problem by raising his float level above spec. Now his carb drips when > he shuts down, but he says it's worth it if it keeps running in flight. > This is a poor solution and is a potential fire hazard. What I've done > on both my coupes is this: Remove the carb, take out the main jet, and > VERY carefully oversize the jet about .002 inch with a jewellers' file. > I know this will make many of you shudder and shake your heads, but it > works! On both of my planes it totally cleared up the problem. > I would really like to hear some of your thoughts on this or any stories > of similar power loss in flight. Comment: My Alon had no RPM peak or EGT peak using the mixture control. It was solved by an FAA Approved Carb Shop by drilling out the main jet several thousandths. Many aircraft use ram air to get more power. The carb shop I worked with said that the reason the mixture is lean is that the same (Marvel) carb is used in other aircraft that use fuel pumps and/or high wings. The higher fuel pressure in these aircraft results in a higher fuel level in the bowl and at the main jet. Raising the float level may also fix the problem, but may introduce others. =================================== __________________________________________________ To unsubscribe from this list please send mailto:[EMAIL PROTECTED] ___________________________________________________________ T O P I C A http://www.topica.com/t/17 Newsletters, Tips and Discussions on Your Favorite Topics
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