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Ok Ed,
Let's do a quick carb-speak check. FLOAT level typically is checked with the carb upside down and the bowl removed. The number is the measured distance from the gasket surface to the highest point on the float unless depicted otherwise in the manual. Remember the FLOAT level is measured with the carb inverted, and the thing to remember is that the higher the FLOAT level the lower the FUEL level. The confusion with the reversed levels is the reason that all the motorcycle manufacturers went to FUEL level only in their specifications. The motorcycle guys gave you a tube which was a simple graduated cylinder, a hose, and a tap screw to put in the bottom of the float bowl. You were supposed to only measure the fuel level. In fact if you look at later model carburetors you will see that the flange that contains the float bowl is cut away in the center so you can see the gasket mating surface. The purpose of the cutaway was to allow you to see the gasket seal surface to measure the fuel level, which used the same reference surface. If you look in the service manual (Kawasaki at least) of a bike with carbs printed in the last 15 years you will see only a fuel level listed. Boy did that cause the mechanics to bitch when they first made the change! When speaking only of the fuel level the understanding is easy. Fuel level high, carb runs rich. Fuel level low, carb runs lean.
Sorry for the long explaination for the very simple concept.
Bill Jepson
-----Original Message-----
From: Ed Anderson <eanderson@carolina.rr.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Mon, Jul 13, 2009 9:30 am
Subject: [FlyRotary] Re: Oly's report on accident
Ok, Bill – you lost me. Must admit
my carburetor knowledge is a bit on the skimpy side.
However, in the carburetors I recall – when the float level was high in the bow that meant there was lots of fuel in the bowl, when the float level was low in the bowl the fuel was also. Am I confused or did you “misspeak” {:>)?
Ed
Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
Finn,
Running Carburetors if the float level is too high, and therefore the fuel level too low, it can prevent the vacuum from raising the fuel enough to keep the engine running. This is less common than the FUEL level being too HIGH which will cause the engine to go rich when the throttle is closed. I see the rich condition far more often.
Bill Jepson
-----Original Message-----
From: Finn Lassen <finn.lassen@verizon.net>
To: Rotary motors in air
craft <flyrotary@lancaironline.net>
Sent: Sat, Jul 11, 2009 4:24 pm
Subject: [FlyRotary] Re: Oly's report on accident
Too high? Now that's a new one. Please explain.
Finn
Al Gietzen wrote:
> I sometimes would have the engine quit > after pulling back on the power while crossing midfield coming in a full > speed from the beach to land at Clearwater airpark
> -------------------------
> Did you ever check the carburetor float levels? Engine dying after pulling
> the power is a symptom of too high a float level.
>
> Just a thought,
>
> Al
>
>
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