Re: 1977 Mercury 850 CDI ignition idel adjustment
Adjust idle speed to achieve the lowest stable idle in gear in the water. This will minimize the shock to the gears when you shift. BTW always shift in and out of gear with a sharp, quick motion. These are not designed to 'ease' into gear.
Your motor will have a "timing" or "spark advance" stop. You don't want to mess with that unless you're doing a tune-up and adjusting your maximum spark advance.
What you're looking for is the "idle stop". If you have ADI (4 coils on the side, no distributor), you've got a long-travel throttle arm on the side of the motor, and the idle stop is located on the exhaust manifold. Loosen the locknut on the stop and adjust so the arm goes to the rear a bit more (slower idle). Be sure to lock the adjustment down when you're done.
You may need to readjust the throttle control cable for the correct preload, after you change the idle stop setting. In Neutral, you should have enough preload to slightly force the throttle arm into the idle stop. When you throttle up then back to idle, the arm should always 'repeat' and go to the stop. If it doesn't quite want to go there, adjust the ferrule on the throttle cable, such that it pushes the throttle lever more into the idle stop.
If you have a belt-driven distributor, the idle stop is on the front of the plate bolted to the distributor; it's the outer-most screw. The inner screws are for wide-open throttle stop and spark advance. Adjustment is similar to the ADI except that the stop controls the motion of the distributor; screw clockwise for more speed, CCW for slower idle.
HTH...............ed
