On Wed, 7 Mar 2001, Max Heim wrote:
> It seems to me that for your hypothesis to be correct, you would have to say
> that, for a given mixture adjustment, throttle position, and needle, that
> the instantaneous state of the float valve and fuel level (open and filling,
> closed and depleting, or in-between) makes a difference in the fuel mixture
> at the carb throat. I don't see how that can be so (barring starvation, of
> course). Given any fuel at all in the float chamber, the pipe going to the
> jet will be filled, and the only thing that controls the flow rate to the
> carb throat is the needle/jet annulus (I love that word!). Am I missing
> something?
This is the way I understand it. Excuse the (bad) ascii art:
here is our float chamber:
+-------+ +----------+
| | | |
| | | |
|*******|***|**********| <-- fuel level
| | | |
| | | |
| | | |
| | | |
| |
+----------------------+
and with the float too low:
+-------+ +----------+
| | | |
| | | |
| | | |
| | | |
| | | |
|*******|***|**********| <-- fuel level
| | | |
| |
+----------------------+
and too high:
+-------+ +----------+
|*******|***|**********| <-- fuel leve
| | | |
| | | |
| | | |
| | | |
| | | |
| | | |
| |
+----------------------+
Now, we know the basic operation of the SU carb. The vaccuum created
from the air moving over bridge draws fuel from the jet.
Ignoring the action of the Piston/Fuel needle, just look at how the
level of fuel would impact how much fuel is drawn. The suction force
of the air can only lift so much. If the fuel is too high, it is
easily drawn into the carb, thus making things too rich. If too low,
not as much fuel is able to rise the longer distance up the jet,
making the carb lean.
Of course, I could be completely wrong, but this is my understanding.
--
Aaron Whiteman - aaronw@wsu.edu - email with subject 'PGPKey' for pgpkey
RCW 19.190 notice: This address is located in Washington State.
My opinions are mine and do not reflect the views of the University.
:wq
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