When stuffing box of water piston of pumps needs re-packing, the same rule will apply, with the exception that little or no grease or tallow should be used upon the packing.
Always keep piston and valve rod packing in a clean place, as any dirt or gritty substance that may become attached to it will have a tendency to cut the rod.
First, take up all “lost motion” and place the engine on the center. This is done by putting the wrist-pin, crank-pin and center of the main shaft in line. To do this accurately, turn the engine until the cross-head is about half an inch from the end of its stroke, and mark the position of the cross-head on the guide.
Place a marker against the edge of the fly-wheel, and make a mark on the fly-wheel opposite the marker, then turn the engine until the cross-head completes the stroke and comes back to the mark made on the guide.
The crank will now be as much below the center as it was above before. In this position make another mark upon the fly-wheel opposite the marker.
Now, midway between the two marks on the fly-wheel, when turned opposite the marker will put the engine on dead center. Next, remove steam chest cover and place the eccentrics about one-quarter turn ahead of the crank in the direction the engine is to run. If the engine is to run “over”, place the throw of eccentric up. If it is to run “under”, place throw of eccentric down.
Then set eccentric carefully at such a point that the valve will have just commenced to open say ¹/₃₂ of an inch on the end that should be taking steam. If there is a rocker arm used which reverses the direction of the motion, i. e., making the valve stem move in the opposite direction from the eccentric rod, the eccentric must be set behind the crank, when the engine is to run “over”, in order that the port may open as the engine turns forward; but if a rocker arm is used merely to multiply the motion without changing the direction, proceed as though there was no rocker arm at all. Next, measure the “lead” which you have given to the valve at end which you have set. This is easily done by pushing a wedge-shaped stick or piece of soft wood into the port opening. The edge of the valve and port will mark the distance it goes in. Turn the engine upon the other center, which will be found as before described, and see if the lead is the same at both ends of the valve. If it is, the engine is properly set. If it is not, move the valve on the stem towards the end having the greatest amount of lead, a distance equal to one-half the difference in the leads. If the equalized lead is more than is necessary, set the eccentric back a little.