let me start by saying i am sorry if this has been asked before, but i couldnt really find anything like this in the search . i installed a new out of the box edelbrock 600 cfm carb with a manual choke on a stock 305. with every other edelbrock that i had, i turned the mixture screw in until the motor started to die, then backed the screw out a turn and a half. do this for both sides and viola! its set. on this new one, i can screw both all the way in and it still idles. am i missing something. i had it idling smooth and even took it for a quick run. seems to be ok, but the screws dont do anything.