Special Tools Required; Valve Yoke - Mack E7 Service Manual

5-101.bk Page 8 Friday, March 17, 2006 11:05 AM
200 SETUP AND ADJUSTMENTS

Special Tools Required

Jacobs feeler gauges:
0.060 inch (1.52 mm) No. 022001
0.080 inch (2.03 mm) No. 018781
0.085 inch (2.16 mm) No. 014177
0.100 inch (2.54 mm) No. 021327

Valve Yoke

Jacobs yokes must be installed on the exhaust
yoke guide pins. Lubricate the guide pin and the
pallet of the yoke with engine oil. Install yoke with
the adjustment screw outboard (toward the intake
manifold side of the engine).
1. Loosen the yoke adjusting screw locknut
and back the screw out several turns.
2. Exert a moderate force on the yoke by
pressing on the rocker arm slipper end. Turn
down yoke adjusting screw until it makes
solid contact with outboard valve stem tip as
sensed by a light drag on the adjusting
screw.
3. Turn adjusting screw an additional 1/6 turn
(60 degrees) clockwise.
A 1/6 turn is equal to one flat on the adjusting
screw locknut.
4. Hold the yoke adjusting screw in this
position while tightening the adjusting screw
locknut. Torque locknut to 33 lb-ft (45 N•m)
using torque wrench J 24407 or equivalent.
Page 7-8
CHECKING YOKE ADJUSTMENT
1. To check the yoke adjustment, insert a
0.010-inch (0.254 mm) thickness gauge
between the yoke and valve stem, at both
the inboard and outboard locations.
Refer to Figure 7-9.
2. Exert moderate force on the yoke by
pressing on the rocker arm slipper end. An
equal drag should be felt on both thickness
gauges. If drag is unequal, readjust yoke
adjusting screw.
Figure 7-9 — Checking Yoke Adjustment
1. Thickness gauge 2. Yoke