Tappet Assembly

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Tappet assembly consists of:
1. A cylindrical tappet, which slides in and out in a tappet guide installed in one of the crankcase sections around the cam ring;
2. A tappet roller, which follows the contour of the cam ring and lobes;
3. A tappet ball socket or push rod socket; and
4. A tappet spring.
Function -  to convert the rotational movement of the cam lobe into reciprocating motion  and to transmit this motion to the push rod, rocker arm, and then to the valve tip, 
opening the valve at the proper time. The purpose of the tappet spring is to take up the clearance between the rocker arm and the valve tip to reduce the shock load when the 
valve is opened. A hole is drilled through the tappet to allow engine oil to flow to the 
hollow push rods to lubricate the rocker assemblies
Solid Lifters/Tappets
Solid lifters or cam followers generally require the valve clearance to be adjusted manually by adjusting a screw and lock nut. Valve clearance is needed to assure that the valve
has enough clearance in the valve train to close completely.

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