Stop the engine and remove the air filter housing. Label all hoses and connectors that are disconnected from the air cleaner housing.
Remove the spark plug tips with high-voltage wires and move them away from the cylinder head cover.
Remove the PCV valve and high-voltage wire bracket from the cylinder head cover. Use a piece of wire to secure the accelerator cable to the side.
Use a jet of compressed air to clean the spark plugs, which will prevent dirt from getting into the engine cylinder after removing the spark plug. Remove the spark plugs.
Using the high-voltage wire of the spark plug of the first cylinder, mark its position on the distributor housing with the number "1". Do the same for the other cylinders (numbers "2", "3", "4"), then remove the cover and disconnect the wires from the ignition distributor.
Remove the cylinder head cover.
By turning the engine crankshaft in the direction of its working rotation using the pulley mounting bolt, set the piston of the first cylinder to TDC in the compression stroke, while the ignition distributor rotor should be aligned with the "1" mark on the ignition distributor housing. Otherwise, turn the crankshaft clockwise one full revolution. Using a feeler gauge, measure the clearance of the exhaust valves in the first and third cylinders and the clearance of the intake valves in the first and second cylinders.
Record the measurement results.
Turn the crankshaft one revolution (the piston of the fourth cylinder is at TDC in the compression stroke) and measure the clearances on the remaining valves.
Record the measurement results.
If the valve clearances are different from the required ones, adjust them.
Rotate the engine crankshaft to a position where the camshaft lobes above the valve requiring adjustment point upward.
Loosen the lock nut and gently turn the set screw in or out until the feeler gauge enters with slight resistance. Use a screwdriver to secure the set screw in place and tighten the lock nut. Recheck the gap.
Figure 2.23. Cylinder head bolt tightening sequence
With the cylinder head cover removed and the engine warm, use a torque wrench to check the tightening torques of the head mounting bolts. Loosen one bolt by turning it a quarter turn, then tighten it to the torque specified in the manual. Repeat this procedure for all cylinder head bolts in the sequence shown in the figure 2.23.
Install the cylinder head cover with a new gasket and tighten the bolts evenly to the torques given at the beginning of the section.
Screw in the spark plugs, install the distributor cap and connect the high-voltage wires. Install the air filter, connect the hoses, connectors and vacuum hoses.
Start the engine and check for oil leaks between the cylinder head cover and the cylinder head.