The adjustment can be made with the water supply on by tightening
the packing nut enough to hold the hydrant closed.
To increase the tension: With the hydrant in a closed position,
loosen the set screw in the side of the pivot. Lift the handle, which
should lift the linkage without moving the stem, to the desired
location and reset the set screw.
To decrease the tension: Lift the handle part way open and loosen
the set screw in the side of the pivot. Lower the handle, which should
lower the linkage without moving the stem, to the desired location and
reset the set screw.
The handle, at the end of the closing stroke, should
"snap" closed.