I have been working on this project for years. My plan is to use MGB HIF4
carbs. They are cheap amd easy to find, also the intigrated float bowl
would allow the carbs to sit level the way ZS carbs do. Yes, they will bolt
on in place of the ZS carbs, but there is a "step-up" in size entering the
manifold from 1.5" to 1.75". My plan is to machine the thick insulating
spacers used with the MG carbs. The reason for the smaller carbs is to
use the whole needle. If you over carb, the dashpots will only rise
a little, even at WOT. I figure that two 1.5" carbs works on a 1.8 liter
MGB and three work on a 3 liter Healey, so three on a slightly warmed
over 2.5 liter TR would work. I would LOVE to have CFM figures for all
of these carbs!
Bill---You're right about the "springs" and their part in raising the
air pistons. As you know, raising these faster also causes a vacuum
drop, so less fuel is pulled out of the jets, now controlled by the
damper assemblies. It's kind of a catch-22. Going to a lighter spring
also requires some needle work down at the fat end, to keep from leaning
out. No free lunch here!
Your idea of using three, smaller carbs sounds good tho, in helping
throttle response. I would think they could easily keep up at the top
end, as well. Don't know the bolt pattern for the 1.5's and some R&D
would again be necessary for proper A/F mix. Such a project would be
for those with a lot of time to dink around, given that not many tracks
have been laid here.
Dick
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