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"It is usual to put the engine on center before setting the valve. First put the engine in a position where the piston has nearly completed the outward stroke, and make a mark M on the guide opposite the corner of the crosshead or at some convenient place." —Derr, 1911

Steam Engine Valve Centered with Piston

"It is usual to put the engine on center before setting the valve. First put the engine in a position…