Re: 1973 135hp hitch
If you connect the engine to a control box and advance the throttle, the engine will open the carb butterflys and advance ignition timing simultaneously. That's normal. If you run without the control box and only move/rotate the small throttle roller on the top carb, all you get will be the carbs opening. (no timing advance.) That could be the problem. I'd be more concerned if the engine did not function properly when correctly hooked up to the control box and the engine is running in the lake in forward gear. It's not good to rev that engine in neutral above 2000 rpm's (when it's not under any load)
