How do you adjust the two screws on a rockchester two barrel carb?

[dissturbbed]

1978 mercruiser 120 hp= I have read the manual and i understand it till I get to the two screws on the bottom of the carb. When i adjust the carb with these two screws do i screw the one im not adjusting all the way in or do I leave it out a bit while i adjust the other one?

 

[fishrdan]

Both idle mixture screws should be screwed in all the was seating them "lightly", then back both of them out 1 1/2 turns, this is the initial adjustment.

Once the engine is warmed up, tweak the screws one at a time, a little in or out, to get the highest idle RPM. You'll be adjusting both screws, individually, back and forth, getting a smooth idle. Once you find the spot where both screws deliver the highest idle, back each screw 1/8 to 1/4 turn to enrichen the mixture a bit. Shoot for about 750RPM running on land off muffs.

Final idle adjustment should be done on the water, with the engine warmed up, idling in gear.

 

[ktbarrentine]

Shoot for about 750RPM running on land off muffs.

May be semantics, but probably should read "on muffs"

 

[airshot]

Your final adjustment needs to be done on the water while underway. It has been my experience that what ever is adjusted on land or with the boat sitting at the dock is just not quite right. Have a friend navigate your boat at idle while you make those final adjustments and you will get a smoother running engine if all else is working properly. Having rebuilt my carb three years back I was having a difficult time getting the adjustments correct. I am a little picky and like having things work properly so after much trying to adjust things, we went for a boat ride and I made final adjustments on a long ride in a canal and then things worked great and still do.