<VV> Carb Rebuilding (added...Fuel Efficiency)

[Craig Nicol]

 Excellent post, Mike. An addition to your comment is some of the "why"
regarding lower float level leading to leaner mixtures. The main well
includes and emulsion tube system that adds air to the fuel as it progresses
to the cluster. The fuel level in the well varies, and as it varies, more or
fewer holes in the emulsion tube are exposed. As more are exposed, the fuel
has a higher percentage of air and the mixture is leaned. The air correction
orifice on the top of the well plays a large role too. This has the effect
of tapering the mixture in steady state conditions and engineers did a ton
of fine tuning in this area.    I learned this and more from Bob Helt's
Carburetor book - an excellent read, if you don't have it. Another tid bit,
something of a shocker, what the target AFR graph for a typical example. I
can't recall the exact numbers, but the highest it got was 13:1 ish and was
as low as 8 or 9:1 at idle! Fuel economy was "relatively" good and fuel was
cheap anyway, so why not go for the max power AFR?
Good thread.
Craig Nicol


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