DETROIT DIESEL 53
Exhaust Valves 1.2.2
Fig. 12 - Relationship Between Exhaust Valve, Insert and Cylinder Head (4 Valve Head)
(Figs. 11 and 12). The 30 face of the insert may be adjusted relative to the center of the valve face with the 15 and 60
grinding wheels.
CAUTION: Do not permit the grinding wheel to contact the cylinder head when
grinding the insert. If necessary, replace the insert.
The maximum amount that the exhaust valve should protrude beyond the cylinder head (when the valve is in the closed
position), and still maintain the proper piston-to-valve clearance, is shown in Figs. 11 and 12. Grinding will reduce the
thickness of the valve seat 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 seat insert.
When occasion requires, the grinding wheel may be dressed to maintain the desired seat angle with the dressing tool
provided-with the grinder set (Fig. 13).
After grinding has been completed, clean the valve seat insert
thoroughly with fuel oil and dry it with compressed air. Set the
dial indicator J 8165-2 in position as shown in Fig. 14 and rotate
it to determine the concentricity of each valve seat insert
relative to the valve guide. If the runout exceeds .002 ", check
for a bent valve guide before regrinding the insert.
4. After the valve seat insert has been ground, 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.
Fig. 13 - Grinding Wheel Dressing Tool of Set J 8165
Install Exhaust Valves and Springs
When installing exhaust valves, check to see that the valves are within the specifications shown in Figs. 11 and 12. Also,
do not use "N" pistons with former four valve cylinder head assemblies unless the valves are flush with the cylinder head.
If the valves are not flush, it may be necessary to regrind the valve seats so that
August, 1972
SEC. 1.2.2
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