Mailing List lml@lancaironline.net Message #40786
From: Lorn H Olsen <lorn@dynacomm.ws>
Sender: <marv@lancaironline.net>
Subject: Re: carbureted lean-of-peak
Date: Tue, 20 Mar 2007 12:25:29 -0400
To: <lml@lancaironline.net>
Bob,

I don't know where your engine came from but I would guess that you got it from a twin Comanche. The only fuel balancing that I have ever heard of on a 4 cylinder carbureted Lycoming is a spacer between the engine and the carburetor on the twin Comanche.

Did your engine come from a twin Comanche? What model is your engine? My engine came new from Lancair and the model is in my signature. Do you know where that spacer can be obtained? How big is the spacer?


Lorn writes:

When I fly lean I have a lot of engine vibration because I
am not injected. I can see my whole right wing vibrate because
of the engine. I then enrich a little to stop most of the vibration.


"bob mackey" <n103md@yahoo.com> writes

The engine is running rough (presumably) because the fuel is not
distributed the cylinders evenly. A relatively easy way to ensure
uniform fuel distribution is to use injectors that can be adjusted
to match each cylinder (ala GAMI). But that's not the only way...
carbureted engines can also run smoothly lean-of-peak (LOP).
I don't know of any obvious way to adjust the fuel distribution
in a carbureted engine, but adjustments to the induction path
can have the right effect. On my O-320, there is a flow
straightener mounted at the carb inlet in the airbox. It is
slightly asymmetric. It can be installed in four possible
orientations. It turns out that one of those orientations
results in pretty good distribution, allowing the engine
to run smoothly LOP.

Has anyone else experimented with fuel-flow balancing
on single-carburetor aircraft engines?
--
Lorn H. 'Feathers' Olsen, MAA, DynaComm, Corp.
248-345-0500, mailto:lorn@dynacomm.ws
LNC2, FB90/92, O-320-D1F, 1,300 hrs, N31161, Y47, SE Michigan


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