Right on Ron, BTW, I'm just the opposite.
The simple mass, spring, damper, and Bernolli priciples of the SU I understand.
Outside of EFI, I can't imagine doing it any other way.
I cannot grasp the discrete circuits of other types of carbs. They are like
the old automatic transmission valve bodies. Little passages and orfices
Plus I hate any carb where I can't adjust the main jet with the engine running.
----- Original Message -----
From: "Ron Soave" <email@example.com>
Sent: Monday, February 09, 2009 10:25 PM
Subject: Re: [Spridgets] Carb dashpot oil.
> --- Dean Hedin <firstname.lastname@example.org> wrote...
> ...a good explanation. A couple of clarifying points -
>> when the butterflys go wide open. The delayed rise is a
>> result of the damper (and
>> naturally the viscosity of the oil in the damper).
> Also, the resistance to the piston rising is greater than the resistance to
>the piston falling.
>> the engine draws more fuel through the main jet.
> Just to clarify if you're wondering how the needle "not rising" increases the
>fuel flow, the piston damping increases the velocity
> of the air across the venturi and the bridge. The rate of fuel flow is
>directly proportional to the velocity of the air, so you
> get a richening effect.
> I can't tune an SU worth a damn, though. The ones on my race car were set up
>by Craig Chima and I was told not to touch them. My
> 1970 Midget has the SUs as they came out of the factory, and my street Bugeye
>has a Weber!
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