Figure 11-8. Checking valve face.

TM 10-3930-630-34

TA067447

Figure 11-7. Allowable head thickness of refaced valves.

(3) Check all refaced or new valves with an

indicator. Valve face should be true with the stem within

indicator as shown in figure 11-8. Place valve in "V"

0.002 inch (0.051 mm). If not, repeat valve grinding

blocks as shown and rotate face against dial

operation.

TA067448

Figure 11-8. Checking valve face.

(4) Lightly coat valve seat with Prussian blue.

j. Inspect springs for cracks, and other damage.

Place valve in position, and rotate valve slightly to

Replace cracked or damaged springs.

transfer pattern to valve face. Pattern must show valve

k. Check valve springs as follows:

contact width of 0.0625 to 0.938 inch (1.58 to 23.8 mm)

(1) Outside diameter should be 0.9688 inch

and must fall well within the width of the valve face. A

(24.6 mm).

margin of at least 0.0625 inch (1.58 mm) on either side

(2) Check valve springs on a valve spring

must be bore of Prussian blue.

tester. The length of the spring with the valve closed,

(5) If contact area is over 0.938 inch (23.8 mm)

under 47 to 53 pounds (21.2 to 24.0 kg), should be

wide, seat must be narrowed by using a 15 degree stone

1.7031 inches (43.2 mm). Minimum weights to reach

to reduce the outside diameter. If less than 0.625 inch

this should be 42 pounds (19.0 kg).

(1.58 mm), use a 60 to 75 degree stone to increase the

(3) Place a load of 96 to 104 pounds (43.4 to

inside diameter. Refer to figure 11-9.

47.1 kg) on spring to simulate a valve open. Length of

(6) Check valve position in cylinder block and refer

spring should be 1.4219 inches (36.1 mm). Minimum

to figure 11-10 for correct seating.

allowable weight to achieve this is 86 pounds (38.9 kg).

(7) After valve seat is correct, retouch seat lightly to

Replace all springs that do not meet the

remove burs or feathered edge.

above

11-5