serious carb issues

bad440 said
jet performance makes bushing kits or send it to holley or proform billet
that screwed all the way in it had to be a vacume leak

the 4 corner screws regulate air not fuel? wouldnt the screw all the way in be leaner. seems you should have to screw it out to give it more fuel with the xtra air.someone school me i,m learning carbs.