Figure 3-11. Rocker arm and valve location
No. 6 piston is near top dead center on its exhaust
are nearly closed and intake valves start to open, then
stroke and the No. 1 piston is in the same position on its
check and adjust valve clearance for No. 1 cylinder.
compression stroke, therefore, all four valves for No. 1
Note. The dual intake and exhaust valves for each
cylinder are closed and lash may be adjusted. The firing
cylinder are actuated by valve bridges. The valve
order of engine is 1-5-3-6-2-4 and if this sequence is
bridge MUST be adjusted first (before adjusting valve
followed, the last for all valves can be checked and
lash) to assure that each valve bridge contact both
adjusted in two complete revolutions of crankshaft.
When adjustment is necessary, proceed as follows to
e. Adjust each valve bridge by loosening locknut
obtain the specified clearance:
on the bridge adjusting screw; then turn the screw
a. Operate the engine until it reaches 180F.
upward (counterclockwise) approximately one turn.
minimum. Stop the engine.
f. Hold down firmly on center of bridge with the
b. Thoroughly clean the valve rocker covers and
fingers of one hand and turn bridge adjusting screw
downward (clockwise) until screw just contacts the valve
Hold screw stationary and tighten locknut
c. Remove the valve rocker cover capscrews,
securely (fig. 3-12 (2)).
rocker cover sealing washers and the rocker covers.
g. Adjust for proper lash by loosening the jam nut
d. Use barring tool (fig. 3-12 (1)) to turn engine
on each rocker arm adjusting screw (fig. 3-13).
until exhaust valves for No. 6 cylinder