[TR] tr-3 carb float bowl

[Randall]

> Also on a related note.  Why is the
> float level so crucial?  It seems that as long as the petrol level is
> above
> the outlet to the carb there should be no problem whether its 1/8th of
> an inch
> from the top or 3/4 of an inch.

The height in the bowl controls the nominal fuel level within the jet.  If
the nominal level in the jet is lower, then part of the venturi vacuum (aka
depression) is used up just lifting the fuel to the edge of the jet.  Hence
less fuel will flow through the jet for a given depression and jet opening.
Thus "float height" has a direct effect on mixture.  However, the effect is
not constant and so adjusting the mixture nut (which changes the opening)
will not fully compensate for the fuel level being too low or too high.

In other words, having the level too low (or too high) also affects the
mixture calibration curve.

Much too high is, of course, another problem, as it can allow fuel to
dribble down the carb throat when the engine is not running, leaving a
puddle in the manifold that can get sucked into the engine and lead to (or
at least aggravate) hot starting problems.

I don't really know, but my guess is that having the bowls slightly off
level won't hurt anything enough to notice on the street.  If you are going
racing, you may notice that the mixture goes rich or lean in hard curves
(but I'm not even sure which direction would be which).  But that's just a
SWAG.

-- Randall