THE VALVE-GEAR IO3 



treme positions and then measuring the distances between 

 the scratches and the edges of the ports. If a difference 

 exists in these measurements, adjust the valve stem by 

 lengthening or shortening it, as the case may require, 

 until the valve travels the same distance past the two ports. 

 Next, place the engine on one of its dead centers, as ex- 

 plained on page 93, and unless the valve shows one 

 thirty-second of an inch opening or lead at the port lead- 

 ing to the end of the cylinder where the piston is, the 

 eccentric is not in the correct position. If it is not, loosen 

 it from the crank-shaft and rotate it until it is about one- 

 quarter revolution ahead of the crank-pin in the direction 

 in which the engine is to run, watching the valve as the 

 eccentric is revolved, until the port has opened exactly 

 one thirty-second of an inch. Tighten the set screw in 

 the eccentric and place the engine on the opposite dead- 

 center, and the port opening will be found to be just one 

 thirty-second of an inch also, providing the work has 

 been carefully done. 



The above instructions apply for setting the valve 

 to run the engine in either direction, it being only neces- 

 sary to see that the eccentric is always a little more than 

 one-quarter revolution ahead of the crank-pin in the direc- 

 tion in which the engine is to run. 



"Case" portable engines are always set at the factory 

 to run "under" unless otherwise ordered. 



Setting a Valve with Link Reverse. After having 



