^As i learn, you'll learn: CAMSHAFT. Controls how the engine
  BREATHS (intake / exhaust - breath in, breath out, valves up,
  valves down). It is also like a MECHANICAL COMPUTER PROGRAM - as
  it turns, it controls how EVERYTHING in the engine behaves.
  Change one a tiny bit (like changing a parameter in a computer
  program), it changes how a function of the engine behaves. it
  seems to be THE part in an engine that people who work on
  engines get REALLY emotional about. it has the most personality,
  it controls the heart that beats, controls the lungs that
  breathe - it is the BRAIN of the system, really.^