TM 5-3810-300-24&P-3
1.2.2 EXHAUST VALVES
Eccentric valve seat grinder adapter set J 6390 is used
in conjunction with J 8165 to grind the inserts in a four
valve cylinder head and consists of the following:
1. Pilot J 6390-1.
2. Grinding wheel (15) J 6390-2.
3. Grinding wheel (30) J 6390-3.
4. Grinding wheel (60) J 6390-4.
Grind the inserts as follows:
1. First apply the 30 grinding wheel on the valve
seat insert.
2. Use the 60 grinding wheel to open the throat of
the insert.
3. Grind the top surface of the insert with the 15
wheel to narrow the width of the seat to the
Fig. 1PAGE 5. Reconditioning Valve Seat Insert
dimensions shown in Fig. 16.
CAUTION:
Engines with 18.7:1
CAUTION: Do not permit the grinding
compression ratios must incorporate
wheel to contact the cylinder head when
valve seat inserts that are no more than
grinding the inserts.
.251" thick to ensure adequate
clearance between the pistons and
If necessary, the grinding wheel may be dressed
exhaust valves.
to the correct seat angle with the tool provided in
the grinder set (Fig. 17).
4. After the grinding has been completed, clean the
valve seat insert thoroughly with fuel oil and dry it
The maximum amount the exhaust valve should
with compressed air. Set the dial indicator J
protrude beyond the cylinder head (when the
8165-2 in position as shown in Fig. 18, and
valve is in the closed position), and still maintain
rotate it to determine the concentricity of each
the proper piston-to-valve clearance, is shown in
valve seat insert relative to the valve guide.
Fig. 16. Grinding will reduce the thickness of the
Total runout should not exceed .002". If a runout
valve seat insert and cause the valve to recede
of more than .002" is indicated, check for a bent
into the cylinder head. If after several grinding
valve guide before regrinding the insert.
operations, the valve recedes beyond these
limits replace the valve seat insert.
Fig.16. Relationship Between Exhaust Valve, Insert and Cylinder Head
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