[SEL] Fuel Intake Compensating Valve Theory/Question

John Hammink jg.hammink at quicknet.nl
Tue Apr 12 09:55:02 PDT 2005


Curt,
I'm not so familiar with Fairbanks, but I guess that the compensating
valve doesn't close properly or sticks somewhere. The air stream
is to open than and you loose your vacuum because the cylinder is
already full of air at any part of the stroke. When someone close the throttle
plate you get vacuum and the fuel sucks into the cylinder and the engine
starts as you say. Mostly there is a spring behind the compensating valve,
maybe it is broken or to weak. 

John H.



> John,
> I too have a question about the compensating air valve on the Fairbanks 
> engines. We have a stand alone Fairbanks engine and air compressor used 
> to build air pressure to start the big Fairbanks at our show grounds.
> We have cranked on that that little engine until there are several 
> bloody hands. Then one of us will finally recall that the throttle plate 
> has to be manually held closed or near closed. It will start instantly 
> then. At rest the governor spring will hold the throttle plate wide 
> open, and I cannot imagine FM intended as part of the starting procedure 
> to hold the throttle closed manually.
> Can you venture a guess as to what might be wrong so we might correct 
> the problem?
> Curt Holland
> Gastonia, NC
> 
> John Hammink wrote:
> 
> >The purpose of the compensating air valve is to insure the correct
> >percentage of fuel in the mixture, regardless of whether the engine
> >is running fast or slow, under full load or idle. The suction of fuel
> >varies with the speed of the piston and the opening in the air intake
> >pipe. The compensating valve compensates for such conditions.
> >I think he found it experimentally after some different designs and
> >constructions.
> >
> >John Hammink
> >Anna Paulowna, Netherlands.
> >jg.hammink at quicknet.nl
> >www.oldengine.org/members/hammink/web
> >
> >  
> >
> 
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