Mack ASET AC - Page 258

REPAIR INSTRUCTIONS, PART 1
Page 245
VALVE SEAT INSERT COUNTERBORE
Refer to Figure 264.
앫 Valve seat counterbore depth (3):
— Exhaust: 0.376–0.372 inch
(9.55–9.449 mm)
— Inlet: 0.364–0.360 inch
(9.246–9.144 mm)
앫 Inlet valve seat insert counterbore diameter
(4): 1.8295–1.8285 inches
(46.4693–46.4439 mm)
앫 Exhaust valve seat counterbore diameter
(5): 1.6885–1.6875 inches
(42.8879–42.8625 mm)
264
Figure 264 — Valve Seat Insert Counterbore Dimensions
INSPECTION
1. With the valve seat insert removed from the
cylinder head, clean the surface thoroughly
with a wire brush.
2. Check the surface finish for smoothness.
Check the counterbore diameter
(Figure 265) with an inside diameter
micrometer. Compare the measured
diameter to specification.
265
Figure 265 — Checking Counterbore Dimensions
1. Exhaust Valve Guide
2. Inlet Valve Guide
3. Valve Seat Counterbore
Depth
4. Inlet Valve Seat Insert
Counterbore Diameter
5. Exhaust Valve Seat
Counterbore Diameter
1. Inside Diameter
Micrometer
2. Cylinder Head
5-111.bk Page 245 Monday, July 10, 2006 2:26 PM