"The ABC's of carburetion are Always Buy Carter". Use the Rochester as a stinky paperweight!

It's possible that your "professional" set the float level too high and gasoline is spilling over into the airstream from the venturi. Look down the carb throat with the engine idling, and see if there are drips of liquid gas coming from the middle off the carburetor. That shouldn't be happening. It's also possible that the cover is warped, and gas is being pulled into the airstream by engine vacuum that's getting into passages where it doesn't belong.
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!