On Diesel engines having so called "low pressure" injectors (Cummins, Detroit 2 strokes, etc.) doing what for Diesel engines is the equivalent of a gas engine major tune up, includes the term "running the rack". This because, the cylinder heads contain separate push rods, rocker arms, pivot shafts, etc. to physically actuate plungers on the injectors. Or, the area where all the mechanicals for actuation are housed.
Victor Borge' in his comedy routine used to say about the English language "It's your language, I'm only using it".
