That whistle is probably caused by a vacuum leak. Check the base mounting nuts for tightness, but don't break an ear off the carb by getting too energetic with the tightening. A propane torch with the gas turned on, but not lit, will help find the leak. With the engine idling,move the torch tip around close to the base flange, and any vacuum lines in the area. When the gas is picked up by the vacuum, engine speed will increase, and it might smooth out, also.
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!