Saturday, 26 May 2012

Valve Clearance


Valve clearance is the distance or gap between the cam and the top of the valve.  Because the engine has a rocker arm between the cam and valve, we measure this clearance as the distance between the cam and the rocker arm pad. We adjust the clearance by turning a set screw located at the end of the rocker arm.  The bottom of this screw effectively rests on top of the valve, so turning the screw clockwise moves the rocker arm up towards the cam (less clearance), and falls away (more clearance) if we turn the screw counter clockwise.We need to occasionally check and adjust valve clearance because the these components wear slightly with use and the clearance may fall out of the specified range resulting in extra wear (not enough clearance) or lost performance and noisy engine (too much clearance). 


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