Re: '56 Elgin 5.5 HP (lean rich settings for top and bottom nob
Top knob is slow-speed adjustment, bottom is high speed...both adjust the gas mixture in the carb. Turn both clockwise until they seat/stop, but don't crank them down hard. Then back the bottom one out, counterclockwise, 3/4 to 1 full turn. Back the top one out about 1 to 1 and 1/4 turns. After you get it running, let it warm up and then run the throttle up to Fast, turn the bottom needle either way until the engine responds and runs best...then richen (counterclockwise) it a little. Then idle it down and adjust the top needle the same way. You'll have to tweak them a little out on the water/boat, unless you do the initial adjustments on the boat, too. Remember the settings for both.