OHV engines 1 This operation should be carried out with the engine cold and the air cleaner and rocker cover removed.

2 Using a ring spanner or socket on the crankshaft pulley bolt, turn the crankshaft in a clockwise direction until No 1 piston is at TDC on its compression stroke. This can be verified by checking that the pulley and timing cover marks are in alignment and that the valves of No 4 cylinder are rocking. When the valves are rocking, this means that the slightest rotation of the crankshaft pulley in either direction will cause one rocker arm to move up and the other to move down.

3 Numbering from the thermostat housing end of the cylinder head, the valves are identified as follows.

Valve No Cylinder No
1 Exhaust 1
2 Inlet 1
3 Exhaust 2
4 Inlet 2
5 Exhaust 3
6 Inlet 3
7 Exhaust 4
8 Inlet 4
4 Adjust the valve clearances by following the sequence given in the following table. Turn the crankshaft pulley 180º (half a turn) after adjusting each pair:
Valves rocking Valves to adjust 7 and 8 1 (Exhaust), 2 (Inlet) 5 and 6 3 (Exhaust), 4 (Inlet) 1 and 2 7 (Exhaust), 8 (Inlet) 3 and 4 5 (Exhaust), 6 (Inlet) 5 The clearances for the inlet and exhaust valves are different (see Specifications). Use a feeler blade of the appropriate thickness to check each clearance between the end of the valve stem and the rocker arm. The gauge should be a stiff sliding fit. If it is not, turn the adjuster bolt with a ring spanner. These bolts are of stiff thread type and require no locking nut. Turn the bolt clockwise to reduce the clearance and anti-clockwise to increase it (see illustration).

21.5 Valve clearance adjustment

6 Refit the air cleaner and rocker cover on completion of adjustment.

HCS engines
7 The procedure is as described previously for OHV engines, but note that the valve arrangement has been altered and is now as shown below. Take care not to overtighten the rocker cover bolts on refitting, as this can result in leaks.

Valve No Cylinder No
1 Exhaust 1
2 Inlet 1
3 Exhaust 2
4 Inlet 2
5 Inlet 3
6 Exhaust 3
7 Inlet 4
8 Exhaust 4