I believe what you want is your automatic choke working.Do you have a repair manuel? If so,it should have all the carb setting info. Automatic choke cover is black plastic which you can turn to adjust if the factory rivets have been drilled and replaced with screws. This is an Edelbrock carb by the way.It won't look like yours exactly if you have stock but they all generally work the same.
Your carb on the drivers side may have only 1 screw for idle.The Edelbrock in the photo has 2.Pink arrow is the adjustment screw that rides on the Fast Idle Cam (yellow arrow).If you don't have this screw your idle adjustment screw rides on your fast idle cam.(its curved with steps on it)
This is where you get the high revs when you start it cold.When its warmed up you can "kick" it off.
Anyway,carbs are a pain in the @@@,and there are a bunch of adjustments to make.Hard to describe them here.Thats's why I mentioned the repair manuel.Haynes,Chilton.....