6
INSTALLATION MANUAL FOR 490A
Slave Piston Adjustment
NOTE: ADJUST THE SLAVE PISTON CLEARANCE
WITH THE ENGINE STOPPED AND COLD.
STABILIZED WATER TEMPERATURE OF
140° F. (60° C.) OR BELOW. EXHAUST
VALVES, ON THE CYLINDER TO BE ADJUST-
ED, MUST BE IN THE CLOSED POSITION.
1. The TDC mark on the fuel pump gear should
already be at 180 degrees from TDC. The
mark on the fuel pump gear should be in the 6
o’clock position on the gear cover. In this posi-
tion the engine brake slave lash on cylinders 2,
4, and 6 can be set. (Fig. 6)
2. Insert the appropriate brake lash feeler gauge
(P/N 3163681(0.090”) or P/N 5572956
(0.067” for L9 2021)) between the brake slave
piston and exhaust head pin on cylinder one.
(Fig. 7, 8)
If brake lash is set improperly, engine damage
may occur.
3. Using the 6 in-lb torque wrench, P/N
3376592, tighten the adjusting screw until the
torque wrench “clicks” or if not using a torque
wrench, until drag is felt on the feeler gage.
4. Using two wrenches, hold the adjusting screw
and tighten the locknut to 35 N•m [26 ft-lb]. If
a light drag is not felt on the feeler gage read-
just as necessary.
5. Repeat steps 2-4 for cylinders 4 and 6.
6. Using the barring tool, Part No. 5299073,
rotate the crankshaft to align the mark on the
fuel pump gear with the top dead center mark
on the gear cover (12 o’clock) (Fig 9).
7. When the engine is in the top dead center
position, Slave Piston Lash can be set on cylin-
ders 1, 3, and 5.
8. Repeat steps 2-4 for cylinders 1, 3, and 5. (Fig.
7, 8)
9. Install the plastic drive cover located on the
front of the engine.
FIG. 8
FIG. 9
FIG. 7
FIG. 6
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