Whine from the carb

[Guy Dudebro]

There's a high-pitched whine coming from my Edelbrock carb, especially when the engine is idling. The noise dies down a bit when I accelerate. I attached a picture. The whine seems to be coming from the part with a small gap in it (choke assembly?) that is below the carb. The black part with the old triangle shaped gasket. What is this part called and what's it function? Should I probably replace? Any help is appreciated. This board and the venerable board members are so helpful as I'm replacing all the parts on my 67 c10.