[amac209]

i've seen an elelbrock carbs where the float tab was bent enough that it wouldn't seat the needle valve. the very first thing to check when working on a carb is the choke. does it open all the way when the engine is warm? try adjusting the choke so it is held wide open.another carb trick is to hold the throttle linkage wide open untill the engine revs up high then hold the choke plate closed with the throttle open untill it almost dies then open the choke. this will make lots of smoke but what it does is suck lots of fuel through the jets and helps clean them out. did you change the fuel filter? if it worked fine before what i would do is get a gasket kit and take everything apart, give it a good cleaning, set the floats and start over. also make sure you don't have any vacuum leaks and make sure the timming is correct. a 600cfm should work fine on a 305.