2. Remove the air filter (carburetor models), or an air duct from the turbo generator to the air intake (turbo models) - Section 3.
3. Disconnect the high-voltage wires from the spark plugs, remove the spark plugs (Section 4); plug the holes with a rag.
4. Disconnect the breather hose, remove the screws and lift the valve cover (photo). Check the gasket - if there is damage or deformation, it must be replaced. Nissan recommends that the gasket be replaced each time the valve cover is removed.
4.4 Removing the rocker arm cover
5. Turn the crankshaft with a wrench by the crankshaft pulley and turn it clockwise, or (for manual transmission only) shift into high gear and roll the car forward.
6. Turn the crankshaft clockwise, the intake valve of cylinder #1 will open and start to close again, then continue to rotate until the black and orange marks on the crankshaft pulley. Cylinder #1 is now at TDC on the compression stroke, and the valves of cylinder #4 will "pump" (inlet valve open, outlet valve closed).
7. Adjust the clearances on valves number 1, 2, 4 and 6 (Figure 1.4). To do this, insert a feeler gauge blade of the correct thickness between the end of the valve stem and the rocker arm. The blade should be firmly seated. If the clearance is incorrect, loosen the rocker arm adjuster screw lock nut and turn the adjuster screw (photo). Once the correct clearance is set, tighten the lock nut.
AL Valve clearance adjustment
Figure 1.4 Identification of intake and exhaust valves
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8. Having adjusted the clearances on the first four valves, turn the crankshaft forward until piston #4 is at TDC on the compression stroke. Valve #1 of cylinder will now "pump".
9. Adjust the clearances on valves number 3, 5, 7 and 8.
10. Install the valve cover and breather hose, spark plugs and spark plug wires, air filter or air duct. Replace the valve cover gasket if necessary.