Idle Speed & Mixture (One Carb. Engines): Buick

With engine idling at correct idle speed, adjust idle mixture screws, one at a time, for highest tachometer and vacuum gauge reading, then turn screw in to lean mixture until tachometer reading decreases 20 RPM or vacuum reading drops off 1/2", turn screw out exactly 1/4 turn to richen mixture. If tachometer and vacuum reading do not return to maximum with this setting, continue to turn screw out 1/8 turn at a time until maximum readings are just obtained. If setting changed considerably, recheck other idle mixture screw setting. Recheck idle speed setting. If necessary to readjust idle speed, recheck idle mixture settings.