PISTON AND CONNECTING ROD
DESCRIPTION
The pistons are made of a high strength aluminum
alloy, the piston skirts are coated with a solid lubri-
cant (Molykote) to reduce friction and provide scuff
resistance. The connecting rods are made of cast iron.
CAMSHAFT
DESCRIPTION
The camshaft is made of cast iron with eight
machined lobes and four bearing journals.
OPERATION
When the camshaft rotates, the lobes actuate the
tappets and push rods forcing upward on the rocker
arms which applies downward force on the valves.
ROCKER ARM
DESCRIPTION
The rocker arms are made of stamped steel and
have a operational ratio of 1.6:1.
OPERATION
When the push rods are forced upward by the cam-
shaft lobes the push rod presses upward on the
rocker arms, the rocker arms pivot, forcing down-
ward pressure on the valves forcing the valves to
move downward and off from their seats.
VALVES
DESCRIPTION
The valves are made of heat resistant steel and
have chrome plated stems to prevent scuffing. All
valves use three bead lock keepers to retain the valve
spring and promote valve rotation (Fig. 9).
Fig. 6 Piston and Connecting Rod Assembly
Fig. 7 Camshaft—Typical
1 – CAMSHAFT
2 – LOBES
3 – BEARING JOURNAL
Fig. 8 Rocker Arms—Typical
1 – CAPSCREWS
2 – BRIDGE
3 – PIVOT ASSEMBLY
4 – PUSH RODS
5 – ROCKER ARMS
9 - 6 2.5L ENGINE XJ
DESCRIPTION AND OPERATION (Continued)
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