Assuming you have the original Carter AFB (3269s manual, 3310s automatic):
(1) two idle mixture control screws in front, screwed into main body at approximately a 30 degree from horizontal angle.
(2) straight bladed screwdriver
(3) 3/4 turn to 1 1/2 turns from LIGHTLY seated.
(4) Chevrolet factory shop manual
It is OK to make basic adjustments to carb, but before major (rebuild) carburetor work, check the ignition system throughly on a diagnostic oscilloscope. NINETY-THREE percent of ALL carburetor problems are ignition. If the previous owner has installed one of the @#$%^&* electronic points replacements, remove it first and put back the points before you adjust the carburetor. A defective ignition system will cause ALL of the symptoms you describe.
And while the only 'Vette I ever owned was a 1963, in my opinion the 1962 was the best looking of them all!
Jon.
