0310259 JOHNSON SCREW,Upper side mount

Valve lash is measured between the rocker arm and the valve stem. All of the clearance measurements and the adjustments must be made with the engine stopped. The valves must be FULLY CLOSED. Valve Lash Check
An adjustment is NOT NECESSARY if the measurement of the valve lash is in the acceptable range. The range is given in Table 1.
Table 1
Check for Valve Lash    
Valves     Acceptable Range for Valve Lash    
Inlet    
0.38 0.08 mm (0.015 0.003 inch)    
Exhaust    
0.64 0.08 mm (0.025 0.003 inch)    If the measurement is not within this range an adjustment is necessary.
Illustration 1 g00417821
Cylinder and Valve Location (A) Exhaust valves. (B) Inlet valves.Crankshaft Positions for Valve Lash Setting
Table 2
Crankshaft Positions for Valve Lash Setting    
The rotation of the crankshaft is viewed from the flywheel end.    
Rotation     Counterclockwise    
Check and Adjust with No. 1 Piston On this Stroke. (1)     Top Center Compression Stroke (2)    
Inlet Valves     1-2-4    
Exhaust Valves     1-3-5    
Check and Adjust with No. 1 Piston On this Stroke.     Top Center Exhaust Stroke    
Inlet Valves     3-5-6    
Exhaust Valves     2-4-6    
Firing Order     1-5-3-6-2-4    
( 1 ) Refer to Testing and Adjusting, "Finding Top Center Position for No. 1 Piston" for more information.
( 2 ) Put No. 1 Piston at the top center position. After the top center position is found and the adjustments have been made for the correct cylinders, remove the top center bolt. Turn the flywheel in a counterclockwise direction by 360 degrees. This puts No. 1 Piston at the top center position on the other stroke. Install the top center bolt in the flywheel and complete the adjustments for the cylinders that remain.Valve Lash Adjustment
Use the following procedure to adjust the valves:
Put the No. 1 piston at the top center position on the compression stroke.Note: See Testing and Adjusting, "Finding The Top Center Position for No. 1 Piston" for further details.
With No. 1 piston at the top center position of the compression stroke, an adjustment can be made to half of the valves. Adjust the valves that are listed in Table 2 for this position.Before any adjustments are made, lightly tap each rocker arm at the top of the adjustment screw. Use a soft mallet to ensure that the lifter roller seats against the camshaft's base circle.
Illustration 2 g00454433
Valve Lash Adjustment (1) Valve stem. (2) Rocker arm. (3) Rocker arm adjustment screw locknut. (4) Rocker arm adjustment screw.
Loosen rocker arm adjustment screw locknut (3). Insert an appropriate feeler gauge between the rocker arm and the valve stem. If the clearance is insufficient to insert the feeler gauge, turn rocker arm adjustment screw (4) counterclockwise in order to increase the valve lash.
Table 3
Valve Lash    
Valves     Dimension of Gauge    
Inlet    
0.38 mm (0.015 inch)    
Exhaust    
0.64 mm (0.025 inch)    
With the feeler gauge between the rocker arm and the valve stem, turn the rocker arm adjustment screw in a clockwise direction. Continue turning the adjustment screw until the valve lash reaches the specification that is provided in Table 3.
After each adjustment, tighten the rocker arm adjustment screw locknut (3) to a torque of 25 7 N m (18 5 lb ft). Then, check the adjustment again.
Remove the top center bolt, and turn the flywheel by 360 degrees in the direction of the engine's rotation. This will position the No. 1 piston at the top center on the exhaust stroke. Install the top center bolt in the flywheel.
With the No. 1 piston at the top center position on the exhaust stroke, adjustment can be made to the remaining valves. Adjust the valves that are listed in Table 2 for this position.
Repeat steps 3, 4, and 5 for these valve adjustments.
Remove the top center bolt from the flywheel after all valve lash adjustments have been made.