Abstract: In diesel engine fuel injectors of the unit injector type, indicia containing needed information are marked or incised on the working face of the follower which drives the pump plunger of the injector, the marking being done in such a way as not to unacceptably interfere with the normal operation of the follower.

Abstract: A diesel engine unit injector is combined with a check valve having fuel delivery passages (notches or slots) with radially-inner edges that are concave in shape whereby areas of relatively high-velocity interfacial flow between the check valve disc and the surface on which it closes are minimized.

Abstract: A diesel unit injector of the EMD type is provided with a tip whose radius is centered below the center of radius of the sac which it encloses, and the sac volume is minimized. The lower face of the nozzle body of the injector is faired in such a manner as to maintain a strong wall cross-section. A system utilizing a set of potential substitute spring seats is used to reset the opening pressure, as upon rebuilding, within narrow tolerances. The nozzle body is shortened and the check valve cage correspondingly lengthened to reduce the length of the injector valve proper. Trapped volume is reduced consistently with fuel flow requirements.