The horizontal line is the idle speed screw or air gap. The left vertical line is the cinch bolt that holds the carb in place (not an adjustment) The middle line is the seat of the idle mixture adjustment. Its turned farther out than usual. But maybe that works for that engine. The right one is the main fuel metering needle, usually called the high speed needle. If your trying to get it to idle for 3 minutes? Try turning in the idle mixture adj. (middle line) One quarter of a turn (clockwise)