Info on Internet says the Holley Weber is about 350 cfm rated as a 2bbl.Use .7 to compare to a 4 bbl,or 245cfm.
10 years ago I wrote an article for Inliners on my many induction experiments on a 261 Chevy.The engine was mild,block and deck milling for about 9-1 compression,Fenton headers,stock head with a quality valve job,cam .428 lift,206 degrees at .050 lift.
Original set up was two stock Rochester off mid 50's 235 car engines Then two Holley Webers,various four barrels on a Clifford intake.Carbs were tuned properly for the engine.All intakes were water heated.
The testing was the subjective "feel" and the time it took between two objects on a back road using full throttle in second gear of a 3 speed from 2000 to about 4200-4400 rpm.This happened over about 2 years time.Just a hillbilly dyno .
Big surprise,the two leaky Rochesters with stock jetting and power valve "jet" reduced about 15 percent were quite good.The Holley Webers had a slight top end advantage as did the four barrels.Going larger than 400 cfm rated four barrels gave no added power in my tests with a rpm limit of 4400.
Best power was from a 500 Holley 2305 staged two barrel,a rare carb..........I also think multiple carbs function a bit better that a single carb of any size.
