I just rebuilt a 1976 3.0 Mercruiser and after some sweat and tears, I got it running. It runs pretty good in the back yard so I took it out to the lake Sunday to give a shot. The engine is bogging down at about 2500 RPM. I checked the timing again and it's good. I readjusted the valves as I thought maybe I messed it up. There is now about 135-150 PSI in each cylinder. But when I pulled the spark plugs, they were completely black, filled with soot. I'm trying to figure out how to adjust the carb. I have a Rochester 2-Barrel that is only about a year old. It has two adjustment screws, and idle screw and a heat choke. Any suggestions on where to set all of these adjustments for a start. I've played with both of the screws while the boat is in the water and I can't figure out what is happening. The manual is useless in this area. Also, what is the best way to set the choke? I'm no amateur, but certainly not a pro. I don't have 69.00 an hour to pay the shop, that's for sure. Help.
