I completely agree with Jon, who, BTW, is recovering from major heart surgery. A 600 CFM carb is WAY too big for that engine. To calculate the theoretical (not actual) CFM of an engine, use a very simple formula- - - - -divide the cubic inch displacement by 2, and multiply that figure by the maximum RPM you plan to run. Then divide that figure by 1728 (cubic inches in a cubic foot). Since most street engines struggle to achieve more than 90% of the theoretical airflow, multiply the theoretical CFM by 0.9. Now you've got a realistic baseline to shoot for when figuring out what size carb to use.
Example: 283 divided by 2 = 141.5 cubic inches. 141.5 X 6000 = 849,000 cubic inches.
849,000 divided by 1728 = 491.3 CFM- - - - -at 6K RPM! 90% of that is 442 CFM.
Why would you need any carb bigger that 500 CFM capacity for street use where high RPM is seldom, if ever a consideration? Or maybe you just really love getting speeding tickets? I'd suggest using a Quadrajet calibrated for a 305 Chevy V8, or one for a 307 Oldsmobile engine. I believe there was also a 260 Olds with a QJ carb. (Nope- - - -all the 260s had DualJet 2 barrels) Both carbs have very tiny primary venturis with triple-stack construction to give extremely efficient low speed performance and HUGE secondary barrels to give unlimited high speed capabilities.
Jerry
