General Description - Perkins 1000 Series Workshop Manual

12
CYLINDER HEAD ASSEMBLY

General description

In a diesel engine there is little carbon deposit and
for this reason the number of hours run is no
indication of when to overhaul a cylinder head
assembly. The factors which indicate when an
overhaul is necessary are how easily the engine
starts and its general performance.
The cylinder head assembly has two valves fitted
for each cylinder, each fitted with double or single
valve springs, according to the engine application.
The double springs have damper coils which are
fitted towards the top face of the cylinder head.
In most engines the face angle of the valves is 45°,
but some engines have inlet valves with a face
angle of 30°. The angle of the valve seats in the
cylinder head are either 46° or 31°.
The valves move in phosphated guides which can
be renewed. The exhaust valve guide has a
counterbore at the bottom and is a little longer than
the inlet valve guide.
Both valve stems are fitted with oil seals which fit
over the top of the valve guides.
Turbocharged engines and some naturally aspirated
engines have valve seat inserts fitted in the cylinder
head for both inlet and exhaust valves. Engines
which do not have valve seat inserts fitted as
standard, in production, can have them fitted in
service.
12A.02 Perkins Phaser/1000 Series, April 1995