12 CYLINDER HEAD ASSEMBLY
To fit valve seat inserts12A-14
1 Remove the valve guide and clean the bore into
which the guide is to be fitted.
2Fit new valve guides, operation 12A-11.
3 With the bore of the new valve guide used as a
pilot, machine the recess in the cylinder head to the
dimensions shown in data and dimensions at the
end of this section, or machine out the old insert.
Remove all debris and clean the insert recess.
4 If the bottom face of the cylinder head has been
machined, the insert will have to be surface ground
on the back face to ensure that there is no
protrusion of the insert above the bottom face of
the cylinder head. After the back of the insert has
been ground, ensure that the outer edge of the
back face has a 0,9/1,3 mm (0.035/0.051 in)
chamfer at 30° to the vertical.
5 With the bore of the valve guide used as a pilot,
and with the rear face of the insert towards the
cylinder head, press in the insert with the valve seat
insert tool, see data and dimensions. Do not use a
hammer on the insert and do not use lubrication.
Use a hydraulic press or a hand press in one
continuous movement. Ensure that the bottom of
the insert is in contact with the bottom of the
recess.
6 Cut the valve seat at an included angle of 88°
for 46° valve seats or 118° for 31° valve seats,
operation 12A-13, and lap the valve on to the valve
seat. Ensure that the depth of the valve head below
the face of the cylinder head is within the
production limits, see data and dimensions. Work
as near as possible to the minimum figure to allow
for future wear on the valve seat.
12A.22 Perkins Phaser/1000 Series, April 1995
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