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2bbl vs 4 bbl F.I. intake



This is from John Landry. I thought you all may want to hear this sounding
theory:

With a four barrel manifold, you have unequal intake runner length when the
carb is operating with only the primaries.  The carb has to sit centered on
the intake, so this forces the primary throttle bores to be located farther
forward in relation to the center of the intake.  So you wind up with
longer runners leading toward the rear of the intake than the front.

Is this enough to matter?  That I don't know, but I'm sure everything
matters to some small degree.  For this reason, it could then be argued
that a two barrel manifold might be better for a throttle body fuel
injection conversion.  I don't think the primary throttle bores on a four
barrel manifold are necessarily larger than the two barrel  manifold.  What
I'm trying to say is that *if* you're planning to use only two barrels to
introduce an air / fuel mixture into the intake manifold, then quite likely
a two barrel manifold is *better* than a four barrel manifold.

A four barrel intake manifold has to compromise equal runner lengths in
order to fit the larger carburetor.  Any losses in performance are
obviously outweighed by just having the four barrel carb.  But if you go to
a two barrel throttle body fuel injection, it might be better to in fact
use a two barrel intake.

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
                        John L Fleck  
                     1225 N.E. McGee Way
                     Pullman, Wa. 99163
        Washington State University College # 509 332-7565 
        E-MAIL  jlfleck@domain.elided                
        ICQ # 8536313                 GOD bless you
        Personal Web Site: http://www.wsu.edu:8080/~jlfleck
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