DS 19 OPERATION No. DS 112-4 : Work on the cylinder head. Op. DS 112-4 82
TOOLS
29 Drain the radiator and cylinder block. Save the water which contains anti-freeze. Unscrew the cylinder head
fixing screws.
Unscrew the inlet rockershaft fixing screws. Raise the rockershaft and disengage the push-rod of the valve in
question. Replace the rockershaft and tighten the fixing screws moderately. When tightening, make sure that
the spherical ends of the adjusting screws are engaged in the sockets of the push-rods. . . . . . . . . . . . . . . . . . . . 21 mm spanner
14 mm box spanner
30 Release the rocker at the side, place the collar MR 4244 in position (see Pl. 17 fig. 4).
With the piston of the valve in question at top dead centre, compress the valve spring (spring compressor
1614-T, see Pl. 5).
If necessary, free off the split cotters by lightly tapping on the edge of the cup with a hammer . . . . . . . . . . . . . Collar MR-4244
Spring compressor
1614-T
31 Remove the split cotters, the upper spring retaining cup, the springs and the sealing ring (30) (see Pl. 3, fig. 2).
Assembly (see Pl. 3).
32 Make sure that the thrust washers (31 and 32) for the springs are in position. Put in position the sealing ring (30),
then the springs and upper thrust cap.
33 Fit the split cotters (collar MR-4244 and spring compressor 1614-T, see Pl. 17, fig. 4).
Raise the inlet rockershaft and fit the push-rod removed in paragraph 29 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Collar MR-4244
Spring compressor
1614-T
34 Offer up the cylinder head fixing screws and tighten (torsion spanner 2471-T, see Pl. 7, fig. 2).
1st tightening 21.75 ft/lbs (3 m.kg), 2nd tightening 43.5 ft/lbs (6 m.kg).
On no account must the tightening torsion of 43.5 lbs (6 m.kg) be exceeded.
Observe the sequence of tightening the screws (see Pl. 7, fig.1). During the tightening, make sure that the tappet
adjusting screws are properly located in the sockets of the push-rods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Torsion spanner 2471-T
14 mm socket
NOTE – It is an obligatory procedure to retighten the cylinder head when a distance of 300 miles (500 km) has
been covered, then 1,250 miles (2000 km) (see Op. DS 112-1, paragraph 19, NOTE).
35 Check the valve rocker clearances 0.008 ins (0.20 mm) for the inlet valves and 0.010 ins (0.25 mm) for the exhaust
valves. If necessary, re-adjust (see Op. DS 112-0).
36 Fit the cups (3) and the rubber joints (4) on the sparking plug tubes (see Pl. 1).
Fit the cylinder head cover, securing the gasket with Hermetic to the cover only. Tighten the nuts (leather
and plain washers).
Fit the 4th sparking plug (spanner 1603-T, see Pl. 16, fig. 7), the bakelite and rubber caps.
Connect the sparking plug leads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 mm box spanner
Spanner 1603-T
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