No idle speed screws on the mechanical linkage,idle speed is adjusted by the air bypass screws on the front of each carb.Open each mixture screw 1 to 2 turns out on both carbs.Set the idle air bypass screw on the front of each carb one turn open then adjust equal amounts in or out until you get the desired idle speed.Start with the front carb and adjust the mixture screws in one at a time until you start to lose rpm.s then back off 1/4 turn,you may have to go back and adjust both again to get it right.make adjustment with interconnecting linkage disconnected.This is a set of 3447 Max Wedge carbs,same set up.