Unfortunately, some rather important info is not in the list of part
specifications you proved. Like, what size are the carbs, and what size
are the chokes? My guess is that he's running main choke (venturi) sizes
in the 32, 33 range, and could be using 28s or so, maybe 30s. Depends on
what sort of proting work has been done on the head, if any, and the cam
timing, and the comression ration, and the ignition system, and all sorts
of things.
Hmm, I should know this of the top of my head, but my autocross Spit with
the 1500 has 28 chokes in it, I think, I don't believe I'm running the 26s.
But then, terms like "idle" and "light throttle" are not part of the tuning
picture there. And it has a stock cam and only 9 to 1 compression. Hey,
only about 10 months before I drag Killer up to Oregon for VTR. I better
get that bonnet spiffed up.
Anyway, too large a choke size can lead to lower air velocity through the
venturi, leading to poor fuel atomization, leading to driveability troubles,
poor gas mileage and throttle response that may not be as crisp as it could
be. Coming off the idle circuit and going onto the main with too large a
choke can give you a bit of a lean miss or stumble, much like lifting the
damper on a constant vacuum carb like an SU or Stromberg can do, depending
on how the mix on that carb is set.
Just tell him to avoid "light throttle!"
mjb.
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