Exhaust Valves
1.2.2
DETROIT DIESEL 53
Fig. 12 - Relationship Between Exhaust Valve, Insert and Cylinder Head (Four Valve Head)
(Figs. 11 and 12). The 30 o face of the insert may be
recedes beyond the specified limits, replace the valve
seat insert.
adjusted relative to the center of the valve face with
the 15 o and 60 o grinding wheels.
When occasion requires, the grinding wheel may be
dressed to maintain the desired seat angle with the
CAUTION: Do not permit the grinding wheel to
dressing tool provided with the grinder set (Fig. 13).
contact the cylinder head when grinding the
After grinding has been completed, clean the valve
insert. If necessary, replace the insert.
seat insert thoroughly with fuel oil and dry it with
compressed air. Set the dial indicator J 8165-2 in
The maximum amount that the exhaust valve should
position as shown in Fig. 14 and rotate it to determine
protrude beyond the cylinder head (when the valve is
the concentricity of each valve seat insert relative to
in the closed position), and still maintain the proper
the valve guide. If the runout exceeds .002 ", check for
piston-to-valve clearance, is shown in Figs. 11 and 12.
a bent valve guide before regrinding the insert.
Grinding will reduce the thickness of the valve seat
insert and cause the valve to recede into the cylinder
4. After the valve seat insert has been ground,
determine the position of the contact area between the
head. If, after several grinding operations, the valve
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
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,
Fig. 13 - Grinding Wheel Dressing Tool of Set
it may be necessary to regrind the valve seats so that
J 8165
SEC. 1.2.2 Page 7
August, 1972
