If I were considering adapting a 2-BBL carb (with a proper manifold design, not an adapter) I'd look at the Dual-Jet Rochester, that's basically the front half of a Quadra-Jet. That carb has a 3-step venturi, and it transitions pretty seamlessly from one RPM range to another. The throttle bores are also small enough to assure adequate venturi velocity to avoid the dreaded off-idle stumble that big bore carbs of all designs tend to have. There MUST be enough airspeed through the venturi to create enough vacuum for good fuel mixing. That's difficult, if not impossible when the throttle bore and the venturi is too large.
Does this site have spelling auto-correct? It keeps converting "venturi" into "venture!"
Jerry
