I was told to tune my carb. by adjusting (while the car was at idle) the two screws on the front of my edlebrock till it was at its highest idle and then adjust the idle speed back to where I want it. It sounds and feels better but is this right? I have a 350 in a 66 chevelle so there is no o2 censor. Is there any other better way without buying some expensive stuff? Should I put a o2 censor in it and add a fuel/air mixture guage?

that way works OK..You can get it closer with a vacuum gauge. Hooked to a full manifold vacuum source you can adjust the 2 screws until you have the highest vacuum..you have to lower the idle and repeat until you have the max vacuum at your idle speed with the idle adjustment screw at its lowest point.