OK Max and others;
If you want to have a real eye opening "practical" educational event,
install an O2 sensor driven Air/Fuel Meter in your car. Tune your carb(s)
with your Colortune, your balancer, your best ear, whatever, and if you are
like any other normal human being, you will be lucky to be able to tell the
difference in mixture adjustment within 1/2 turn.
Then watch your A/F Meter.You can move the meter right off the
stoichiometric point with 1/4 turn. Can't see it on the tach, hear it in the
exhaust, but you can see it on the meter. Very small adjustments make a
significant difference. Probably why some times your "tuning" efforts are
better than others.....Fuel level height is one of those variables that make
this so much fun.
Dave Munroe
----- Original Message -----
From: "Max Heim" <mvheim@studiolimage.com>
To: "MG List" <mgs@autox.team.net>
Sent: Friday, March 09, 2001 1:41 PM
Subject: Re: SU Adjustments (LONG!) was: Float Height Issue
> OK, I admit this is more complicated than I thought...
>
> I'm still a little dubious that a pressure differential of .0012psi could
> make any discernable difference (difference of + or - 1/32nd inch fuel
> depth, which is about the difference one washer thickness would make).
>
>
> > Charley & Peggy Robinson wrote:
> >
> >> The atmospheric
> >> pressure in the bowl pushes the fuel thru the jet into the lower
> >> pressure environment in the venturi. Now, we know that as you go
deeper
> >> in a body of water, the pressure increases.
> >
> > ...at a rate of 0.465psi per foot. A twelve foot deep pool produces a
> > pressure of 5.6psi or about 1.4 bar absolute. But I digress...
> >
> >> The same thing happens in
> >> the microcosm of the float bowl, albeit the pressure change is very
> >> small. That's why the float height affects the mixture. When you
tweak
> >> the needle adjusting nut, you compensate for that, among other things.
> >>
> >>
> >> Cheers,
> >>
> >> CR
> >
>
> --
>
> Max Heim
> '66 MGB GHN3L76149
> If you're near Mountain View, CA,
> it's the red one with the silver bootlid.
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