Smallblock 2x4 setups

Offy made or still does make 2x4 spreadbore intakes.

When you run dual 4's you don't add up both carbs to determine the cfm of the carbs to use, it does not work that way. Look at the 340 6 barrel and 6 pack they have approximately 1050cfm if you add up all 3 carbs and this is a stock motor. Like rumble says it is set-up dependent.

Don't get to caught up in formulas, equations and dynos (both computer program & mechanical) etc. These are just tools and guidelines after all we race and drive cars not formulas, etc. There are way to many variables for a formula to work 100% correct. For that matter on a dyno it only reads torgue, your horsepower is a formula of your torque and rpm.

Something else that can be done if it is street driven alot is use progressive linkage. Buick did this on their 2x4 setup on their nailhead 401 and 425. These engines ran off the back carb during part throttle cruise because the primaries on that carb are closest to the middle of the intake. When you got to about half throttle the front carb started to open up and of course if you mashed the throttle both carbs were open fully. Being the carbs have different opening rates the front carb had the linkage mounted closer the throttle shaft than the back carb because it needed to open at a faster rate than the back carb.

Chuck