I think the claim that was being made a while back was that, if a 44 is
choked down to the same size as a 40 (let's say 34, which was a pretty
common street size), the air flow velocity through the choke will be the
same in both carbs, but downstream of the choke it will drop quite a bit
more in the 44 (bigger cross-section means lower velocity for a given flow
volume). This will make the 44 more susceptible to inconsistent fuel
mixture, etc. Basically that's true.
But what is missing is that the downstream velocity is determined by the
manifold size and the port size. If these are the same in both cases, the
flow velocity will be the same. The only way you could get the full benefit
of the "lower disruption" 40mm carb would be if the manifold and ports were
sized to match.
A 44mm bore has an area of 2.35 sq in. A 40mm bore is 1.92 sq in. Now, as an
exercise for the reader, go measure your manifold and ports.
Gordon Glasgow
Renton, WA
-----Original Message-----
From: owner-datsun-roadsters@autox.team.net
[mailto:owner-datsun-roadsters@autox.team.net]On Behalf Of Chris
Robertson
Sent: Saturday, January 27, 2001 8:33 PM
To: datsun-roadsters@autox.team.net
Subject: Re: Solex carbs 44mm vs 40mm
True, BUT...all you do is put in smaller diameter chokes. You can make the
44's as small as the 40's, but you can never make the 40's as large as the
44's!
Chris
> > >From: "aryasura" <aryasu19@idt.net>
> > >Reply-To: "aryasura" <aryasu19@idt.net>
> > >To: <datsun-roadsters@autox.team.net>
> > >Subject: Solex carbs 44mm vs 40mm
> > >Date: Sat, 27 Jan 2001 22:06:44 -0500
> > >
> > >I saw this posted to the web recently.... is this guy correct in
>preferring
> > >the 40mm over the 44mm?
> > >If so, how come everyone uses 44mm on our roadsters?
> > >
> > >"Let's say your engine makes 150 hp with either a set of 44mm carbs or
>40mm
> > >carbs.
> > >Use the 40mm; they will give you a higher air velocity through the
>power
> > >band.
> > >This means better efficiency in terms of throttle response, fuel
> > >atomization
> > >and economy.
> > >Horsepower is measured and determined by air flow so take all you can
>get
> > >as
> > >long as you get good flow and velocity all the way through the rpm band
>and
> > >your engine is equipped to handle it."
> > >
> > >-ed
> >
> > _________________________________________________________________
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> >
>
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