Note: Adjustment of clearances in the valve drive mechanism must be carried out on engines without hydraulic tappets - i.e. on engines manufactured before October 1984. Checking and adjustment can be performed on both a cold and a hot engine.
1. Remove the camshaft cover as described in Chapter 2A.
2. Disconnect the low voltage plug on the electronic ignition control unit (see Chapter 5B).
3. Using a suitable wrench, turn the crankshaft by the crankshaft pulley bolt in the normal direction of rotation so that the intake and exhaust cams of the first cylinder point down from the rocker arms.
4. Using a flat feeler gauge of the recommended clearance thickness, check that the feeler gauge can be pulled between the valve stem and rocker arm with slight force (see fig. 28.4). Note that the intake valves are located in the cylinder head on the intake manifold side, and the exhaust valves on the exhaust manifold side. The clearances for the intake and exhaust valves are different.
Fig. 28.4. Checking the clearances in the valve drive mechanism between the valve stem and the rocker arm with the camshaft cams facing downwards
5. If adjustment is required, loosen the lock nut, turn the rocker arm adjusting screw to set the required clearance and tighten the lock nut while holding the adjusting screw still.
6. When the clearances of both valves of cylinder No.1 are set, turn the crankshaft to set the cams of the next pair of valves (cylinder No.2) down, and adjust the clearances of these valves in the same way. Repeat the steps for cylinders 3 and 4.
7. When finished, install the camshaft cover as described in Chapter 2A.