Got a Edelbrock 1406 carb on my 383. Started having idle issues, rough and erratic RPM's. Saw an Edelbrock video showing if experiencing idle problems, one thing to try is to remove both idle mixture screws and blow compressed air into the screw holes to clear any dirt may be blocking the small passages for idle fuel flow. Then replace idle screws turning full in to gently bottom out and then back off both by 1- 1 1/2 turns to get you into the ball park for idle mixture. Worked perfectly, solved the problem. Of course, you probably want to go through the procedure to fine tune idle mixture with vacuum gauge as covered in the carb instructions after.
