Alternator help please

About two weeks ago I just installed a brand new aloternater but what I've noticed is that it makes a weird wissing noice when I use the lights and stuff. Ive never heard a car do that. I need to rev up my car when I stop or the car starts shaking and the lights dim. help me out please.

i dont think u installed it right. i think u need ot recheck to make sure stuff is tightened properly and thats your belt has good tension. becuase this being loose will cause the flapping of the alternator.

Yea my car does that aswell, when it idles it shakes a little with the lights on or fan. The garages here say its normal because it isnt cutting out and its charging fine at 13.5V. Thats at 900rpm idle since i got the carb redone but you could always just bring it up a little, the garages say it doesnt really matter what you idle it at as long as it isnt over revving