CAMSHAFT, ROCKER ARMS, PUSHRODS (VALVE TRAIN) MICKEY HO 4M – D

CAMSHAFT Lobes (Key component) Arrangements Controls opening and closing of intake and exhaust valve Timed with motions of piston in cylinder Arrangements Single overhead cam Double overhead cam Pushrod

Timing for Intake and Exhaust

SOHC and DOHC SOHC – one cam per head DOHC – two cam per head Cam controls both intake and exhaust DOHC – two cam per head Intake and exhaust each has a cam Four or more valves per cylinder Advantage Disadvantage Higher engine speed Breakage in timing belt/chain

PUSHROD Camshaft inside engine block Uses pushrods to control valves Less prone to breakage Limit engine speed

REFERENCE http://auto.howstuffworks.com/camshaft.htm http://en.wikipedia.org/wiki/Four_stroke_engine http://www.allpar.com/eek/cams.html http://www.4cycle.com/karting/html/cam_theory.html