DETROIT DIESEL 53
Exhaust Valves 1.2.2
Fig. 11. - Relationship Between Exhaust Valve, Insert and Cylinder Head
2. Use the 60 grinding wheel to open the throat of the
Grinding will reduce the thickness of the valve seat
insert.
insert and cause the valve to recede into the cylinder
head. If, after several grinding operations, the valve
recedes beyond the specified limits, replace the valve
3. Then grind the top surface with a 15 wheel to narrow
seat insert.
the width of the seat from 3/64" to 5/64" (Fig. 11). The
30 face of the insert may be adjusted relative to the
center of the valve face with the 15 and 60 grinding
When occasion requires, the grinding wheel may be
wheels.
dressed to maintain the desired seat angle with the
dressing tool provided with the grinder set (Fig. 13.)
CAUTION : Do not permit the grinding
After grinding has been completed, clean the valve seat
wheel to contact the cylinder head when
insert thoroughly with fuel oil and dry it with compressed
grinding the insert. If necessary, replace the
air. Set the dial indicator J 8165-2 in position as shown
insert.
in Fig. 13 and rotate it to determine the concentricity of
each valve seat insert relative to the valve guide. If the
The maximum amount that the exhaust valve should
runout exceeds .002", check for a bent valve guide
protrude beyond the cylinder head (when the valve is in
before regrinding the insert.
the closed position), and still maintain the proper piston-
4.
After the valve seat insert has been ground,
to-valve clearance, is shown in Fig. 11
determine the position of the contact area between the
valve and the valve seat insert as follows:
a. Apply a light coat of Prussian Blue or similar paste to
the valve seat insert.
b. Lower the stem of the valve in the valve guide and
"bounce" the valve on the seat. Do not rotate the valve.
This procedure will show the area of contact (on the
valve face). The most desirable area of contact is at the
center of the valve face.
After the valve seat inserts have been ground and
checked, thoroughly clean the cylinder head before
installing the valves.
Install Exhaust Valves and Springs
Fig. 12. - Grinding Wheel Dressing Tool of Set
When installing exhaust valves, check to see that the
J 8165
valves are within the specifications shown in Fig, 11
1972 General Motors Corp.
February, 1972
SEC. 1.2.2 Page 7
