You can, for starters. With the engine off, turn each of the idle mixture screws clockwise until lightly seated. Record the number of turns for each; they should be very nearly even.

Back each screw out 2 1/2 turns and run the engine until warm and the choke fully off. Turn each screw clockwise 1/2 turn and see if RPM drops or engine stalls. If so, back out each screw 1/4 turn and repeat. If not, turn in another 1/2 turn each. Ideal will be just at RPM drop or a little leaner (clockwise is leaner). Be sure to turn both screws the same amount, alternating between them.

I've had Quadrajets with the "ideal" at 2 1/4 turns out, others at 3 1/2.