Cylinder Head And Pistons - Decarbonising - Opel Kadett Owner's Manual

9.15 Fitting a valve to its guide
specification, replace them all. Springs suffer
from fatigue and it is a good idea to renew
them even if they look serviceable.
12 Check that the oil supply holes in the
rocker arm studs are clear.
13 The cylinder head can be checked for
warping either by placing it on a piece of plate
glass or using a straight-edge and feeler
blades. Slight distortion may be corrected by
having the head machined to remove metal
from the mating face.
14 Valve guide renewal is necessary if the
valve stem clearance in the guide exceeds
that specified. Renewal, or reaming to accept
oversize valves, should be left to a GM dealer.
15 Commence reassembly by lubricating a
valve stem and inserting it into its guide (see
illustration).
16 Fit the valve stem oil seal, using the
protective sleeve supplied with the new seals
over the valve stem to avoid damage.
9.20 Compress the spring and fit the
collets
9.24a Fitting a rocker arm . . .
9.17 Fitting an exhaust valve rotator
Lubricate the sleeve and push on the seal,
ring downwards. Recover the sleeve.
17 On exhaust valves, fit the valve rotator
(see illustration).
18 Fit the valve spring and collar, with the
recessed part of the collar inside the spring
(see illustrations).
19 Place the end of the spring compressor
over the collar and valve stem and, with the
screw head of the compressor over the valve
head, screw up the clamp until the spring is
compressed past the groove in the valve
stem. Then put a little grease round the
groove.
20 Place the two halves of the split collar
(collets) into the groove with the narrow ends
pointing towards the spring (see illustration).
The grease will hold them in the groove.
21 Release the clamp slowly and carefully,
making sure that the collets are not dislodged
from the groove. When the clamp is fully
released the top edges of the collets should
be in line with each other. Give the top of each
spring a smart tap with a soft-faced mallet
when assembly is complete to ensure that the
collets are properly settled.
22 Repeat the above procedure for the other
7 valves.
23 The rocker gear can be refitted with the
head either on or off the engine. The only part
of the procedure to watch is that the rocker
nuts must not be screwed down too far or it
will not be possible to refit the pushrods.
24 Next put the rocker arm over the stud
followed by the pivot ball (see illustrations).
Make sure that the spring fits snugly round
the rocker arm centre section and that the two
9.24b . . . and its pivot ball
OHV engine 2A•7
9.18a Fit the valve spring . . .
9.18b . . . followed by the spring collar
bearing surfaces of the interior of the arm and
the ball face, are clean and lubricated with
engine oil.
25 Oil the stud thread and fit the nut with the
self-locking collar uppermost
illustration). Screw it down until the locking
collar is on the stud.
10 Cylinder head and pistons
- decarbonising
1 This can be carried out with the engine
either in or out of the car. With the cylinder
head removed, carefully use a wire brush and
blunt scraper to clean all traces of carbon
deposits from the combustion spaces and the
ports. The valve head stems and valve guides
should also be freed from any carbon
deposits. Wash the combustion spaces and
ports down with petrol and scrape the
cylinder head surface free of any foreign
9.25 Fit the nut with the self-locking collar
uppermost
2A
(see