Quote:
Originally Posted by SYCARMS
What makes this confusing is in the automobile field one chooses the correct carb using cfm. The motorcycle world does not go by cfm but rates their carbs in mm's. The mm's don't tell the flow rate.
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And of course, every knucklehead out there still dumps a 4100 or larger series double-pumper on their stock sbc and says it runs in the 10s ...
I think it really boils down to the way these3 particular carbs function. the draw-through is a venturi designed to up the velocity. you'd have to have a smaller carb than tract sizes on both ends to make it work effectively. if the carb is too big the velocity will drop too fast feeding into tracts that don't pull enough volume to take advantage of the pressure differential created.
sort of like the issues the big three had with the tunnel port heads developed in the late 60s for trans am and nascar ---just too much tract volume needing to stay in way too high of a rev range to sustain the necessary rate to make them work effectively.