1.If after adjusting the idle mechanism, the engine does not run smoothly, go back to making air and fuel adjustments and repeat the steps for both air and fuel and idling adjustments.
2.If your car is equipped with a tachometer, you can use this as a tool to adjust idling speed (revolutions per minute or RPMs). Check your owner’s manual for the correct RPMs.
3.Tightening the idle adjustment screw increases idling speed while loosening the screw decreases idling speed.
4.There are some cars that have multiple carburetors, i.e. European and Datsun, that must also be balanced for air flow before adjusting.
5.There is a difference in idle speed with the car in neutral/park versus in gear for an automatic car. Do not adjust idle speed with the car in gear unless there is someone in the driver’s seat with their foot on the brake.