Typical Tecumseh carb linkage on 9.0 HP Craftsman (made by Murray) snowthrower.
To set the governor: 1.) Set throttle control to high speed position; 2.) Loosen the governor set screw (#2, red); 3.) Move governor fully clockwise (viewed from above) while keeping the governor lever and carburetor linkage in the fast position as indicated by arrows. 4.) Tighten the screw. When set correctly the linkage and lever can be moved freely from closed throttle to wide open throttle and back.
The high speed is typically set to 3600 rpm. Turning the screw clockwise increases the speed.