帕金斯柴油發動機3008氣缸頭組件

Cylinder head assembly
General description
The two cylinder heads, which are both the s ame, are
made from high quality cast iron. They are machined
on the top and bottom faces for the rocker box and the
cylinder head gaskets respectively . Joint faces are
machined on the inner and outer sides for the
induction and exhaust manifolds.
There are passages for coolant in the cylinder head
around the valve guides and the pockets for the fuel
injectors. The valve guides are made of an alloy of
high quality nickel chromium and are a press fit in the
cylinder head.
The valve seat inserts are cooled and pressed into
recesses which are machined in the cylinder heads.
The inlet valves are made from steel forgings and the
exhaust valves are made from solid nimonic alloy.
Valves are retained with collets, springs and spring
seat washers. Exhaust valves are fitted with valve
rotators instead of upper spring seat washers. Each
set of two valves is actuated by a bridge piece. There
is an adjustment screw and lock nut on the outer arm
of each bridge piece. A nitrided button is inserted in
the top face of each bridge piece and connects with
its rocker lever. Each rocker lever is operated by the
camshaft through a push rod and tappet.

The rocker levers have adjustment screws and lock

nuts to set the tappet clearances. For early engines,

they are assembled on a main shaft in each rocker

box. The rocker boxes are held in the correct

positions on the cylinder heads by  spring dowels and

are retained by cap screws with socket heads and

bolts . The rocker box covers are made of cast

aluminium and are retained by bolts and setscrews.

New engines do not have rocker boxes. Each rocker

shaft is mounted on four pedestals which are retained

by bolts to the relevant cylinder head. A deep rocker

cover protects the roc ker assembly. For these

engines a different type of fuel injector is used. These

fuel injectors are longer and have the connections for

the leak-off fuel above the rocker covers.

The four fuel injectors in each cylinder head are

retained by clamps and cap screws. On early

engines, the connections of the pipes for the fuel

supply and the leak-off fuel are sealed at the rocker

box covers and the walls of the rocker boxes

respectively, to prevent leakage of oil and the entry of

Perkins4008搖臂蓋

To remove

1  Disconnect the batteries.

2  Release the banjo connection bolts from the fuel

injectors and remove the leak-off fuel pipes (A1).

3 Disconnect and remove the relevant high pressure

fuel pipes (A2).

4  Remove the 12 bolts which retain the pedestal

rock er cover (A3) and remove carefully the cover.

To fit

1  Fit a new joint onto the cylinder head and fit the

pedestal rocker cover. Fit the bolts, complete with

plain and spring washers, through the pedestal rocker

cover and into the cylinder head. Use the sequence

given (B) and tighten lightly all of the bolts evenly and

gradually, then use the same sequence (B) and

tighten the bolts to a torque of 23 Nm (17 lbf ft).

2  Before they are fitted, all fuel pipes must be

inspected for cracks or other damage and, if

necessary, renewed. Fit all other components which

were removed in the reverse sequence to their

removal and connect the batteries.