Re: mercury inline six carbs
You have a CDI-Battery model if you have a distributor. The idle speed screw is on the plate that bolts to the distributor. It should be the one on the outside (right) as you're looking from the front of the motor. You should see cast-in letters reading "Idle Stop" or similar.
DO NOT, repeat Do Not mess with the screws on the inboard (left) side of the plate (as you're looking at it from the front), these should be marked "Spark Advance" and "Throttle Stop" or similar.
If you study the screws carefully you'll see that as the throttle is reduced, the distributor rotates and ultimately hits the Idle Stop. To increase idle speed, you'd loosen the 1/4-20 locking nut on the idle adjust screw and then turn the screw clockwise. When you get to a stable idle speed, lock the nut down and then adjust the idle mixture screws as previously described.
If you're having a lot of trouble getting anything adjusted, it might do to study the Clams Canino "Link and Sync" posting which describes how to set up the relationship between carbs' linkages and distributor timing.
BTW, as you increase or decrease idle speed with the Idle Stop screw, it's going to change the tension on the throttle cable. If you make large adjustments to the idle speed, you're going to need to adjust the cable.
To do that, place the remote control in Neutral then unlatch the cable clamp on the shifter arm inside the motor; pull the throttle cable (the top one) out of the fixture and turn the ferrule on the cable such that when you reinstall into the cable clamp, the distributor is being forced into the Idle Stop with just a bit of tension.
If you don't get enough preload on the cable, the distributor won't return to the idle stop every time. If you get too much, the throttle will be stiff and you won't get as much effect with the "fast idle" feature on the control box.
As long as the distributor returns every time to the Idle Stop without being real tight, you've got it.
HTH & G'luck........ed
