Valve Opening and Closing Angles – the angles (usually measured in crankshaft degrees) when the valves first leave and then return to their seats.

Duration - This is the number of degrees the valves are "off their seats" in the four stroke cycle. Duration is usually expressed in crankshaft degrees. Duration may also refer to the number of crankshaft degrees that the lift is greater than a specified value, e.g. duration at 0.050 lift.

Lobe Lift (gross lift) – The difference between camshaft lobe height and lobe width. For an installed cam, lobe lift may be measured from the lifter.

Valve Lift (actual lift) – This equals lobe lift less the tappet gap measurement or it is the lift measured from the top of the valve.

Valve Clearance (Tappet Gap) or Valve Lash – The maximum space between the end of the valve stem and the lifter.

Overlap – This is the number of degrees of duration that the intake and exhaust valves are open at the same time.

Full Lift or Lobe Centerline – The centered point of the highest lift of a cam lobe, expressed in crankshaft degrees.

Lobe Center Angle or Lobe Separation Angle – The angle formed between the full lift of the intake lobe and the full lift of the exhaust lobe for a cylinder, expressed in camshaft degrees.