You are making a common mistake, regarding the capacity of twin SU's on
MG.s
So far as any given cylinder is concerned, it will only "see" the throat
at the end of it's intake runner (port). In the case of twin SU's, that
is only one (1) of the two carbs. In other words, the maximum flow for
any given cylinder is limited by the flow on one carb, not two.
Although, there is a balance tube between the two, it serves only to
help maintian some semblence of vacuum balance on the two intake ports.
(It is not, nor does it act like a plenum chamber.)
But one carb won't feed both cylinders.
The DGV, on the other hand, does have a plenum under the throttle
plates, whereby both intake ports can feed from a single source/carb.
Because only one cylinder is on intake at any given time, the effect is
that the one carb will feed that cylinder, til the intake closes, and
another intake opens, and so on and so on.
With twin carbs, any given cylinder is fed by its carb, and unless the
next intake stroke is the cylinder it's siamesed to, that carb, in
effect, is at rest.
Were you to modify the DGV for simultanious opening of both barrels, you
would most likely flood the engine, especially at WOT (Wide Open
Throttle) at low engine speeds.
Rick Morrison
72 MGBGT
74 Midget
On Thu, 24 Sep 1998 08:21:53 -0400 "wizardz" <wizardz@amdyne.net> writes:
>Correct me if I'm wrong but going from two HS4's
>(2x1.5" throats) to the 32/36 mm progressive
>opening of the DGV seems to me to be a reduction
>in the flow volume the engine can breath unless
>you put your foot 3/4's the way down to open up
>the second venturi.
>??? Has anyone ever modified the linkages to open
>both venturi's in tandem so you have a closer
>volumetric breathing rate as the dual SU's??
>Paul Tegler
>Twin 73 B GTs YB and OB
>YB born 8/72 (Primrose) Yellow BGT
>OB born 1/73 (Blaze Red) Orange BGT
>email: wizardz@amdyne.net
>http://www.amdyne.net/~ptegler/mgmain.htm
>
>
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