You have either a high float level or a too-high idle speed. If the engine is running fast enough to draw fuel through the venturis, the idle mixture screws will have little effect on the idle. If the fuel level is high enough to allow gas to drip from the venturis, it will be necessary to raise the idle speed to keep the engine from stalling. You should not be able to see any fuel flow from the venturi stack at idle speed.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!