TM 5-3895-359-14&P
Recondition Exhaust Valve and Valve Seat
An exhaust valve which is to be reused may be refaced,
if necessary (Fig. 11). To provide sufficient valve
strength and spring tension. the edge of the valve at the
valve head must not be less than .031 " in thickness and
must still be within the specifications shown in Fig. 14
after refacing.
Before either a new or used valve is installed, examine
the valve seat insert in the cylinder head for proper
valve seating. The proper angle for the seating face of
the valve is 30 and for the valve seat insert it is 31 .
When a new valve seat insert is installed or an old insert
is reconditioned, the work must be done with a grinding
wheel (Fig. 12).
The eccentric grinding method for reconditioning valve
seat inserts is recommended. This method produces a
finer, more accurate finish since only one point of the
grinding wheel is in contact with the valve seat at any
time. A micrometer feed permits feeding the grinding
wheel into the work .001 " at a time.
Fig. 12. Reconditioning Valve Seat Insert
Eccentric valve seat grinder set J 7040, which includes
Grind the inserts as follows:
the grinder, dress stand and pilot, and dial gage, is used
to grind the inserts. An adaptor set which includes the
1. First apply the 31 grinding wheel on the valve seat
grinding wheels and pilot is used with the grinder.
insert.
Adaptor set J 8165-8, used for the two-valve cylinder
2. Use the 60 grinding wheel to open the throat of the
head, consists of the following:
insert.
1. Pilot, tool J 8165-3.
2. Grinding wheel (15 ), tool J 8165-4.
3. Grinding wheel (31 ), tool J 8165-5.
4. Grinding wheel (60 ), tool J 8165-7.
Fig. 13. Determining Concentricity of Valve Seat
Insert with Dial Indicator
Fig. 11. Refacing Exhaust Valve
10-2-42