[HO455]

Changing your timing won't change the position of your throttle blades. Change the timing so your engine idle speed goes up. Then you will loosen the idle set screw on the carb to lower the idle speed back to normal. Your the one moving the position of the throttle blades lower. This will drop the edge of the throttle blade below the idle transition slot and then your idle screws should have the ability to change your idle quality. The photo shows the bottom of the carb and most likely yours is like the bottom photo.