My understanding of a Holley or Carter carb as used on a race car is just that,
they are velocity based and make fuel adjustments according to CFM of air not
lbs of air. hence my issue with the altitude change needing a jet change to go
with it. The CFM at altitude is the same as at sea level because it is a
mechanical function of the engine. It will consume just as many CFM at 4000 feet
it will consume less lbs of air though. The variable air bleed sounds very
interesting though...
Dave Dahlgren
"Thomas E. Bryant" wrote:
>
> List,
> I think some are getting their terminology confused. There are altitude
> compensators on many of the later carburetor systems, actually air
> bleeds to lean the system at altitude.(parameters: closed below and open
> above 5000') Although some may be part of the carburetor, most are
> usually a Baro device separate from the carburetor connected by a hose.
> These are designed for street use, not really applicable to what we do.
> Since carburetors work on velocity, they are somewhat flexible with
> altitude changes because the atmospheric pressure changes, but there
> comes a time when physical adjustments are needed. One carburetor that
> may be similar in function to what is being proposed is the Ford
> Variable Venturi Carb (4300) which works on the same principle as the
> motorcycle carbs that Jon mentions.
>
> Tom, Redding CA - #216 D/GCC
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