3408 & 3408B DIESEL TRUCK ENGINE Caterpillar


Valves, Valve Springs And Valve Seat Inserts

Usage:

NOTE: Guidelines For Reusable Parts; Valves And Valve Springs. Forms SEBF8002 and SEBF8034, have the procedure and specifications necessary for checking used valves and valve springs.

(1) 4N5906 Spring for valves (new):

Length under test force ... 54.99 mm (2.165 in.)

Test force ... 344 ± 34 N (77 ± 7.6 lb.)

Use again minimum load at length under test force ... 291 N (65.4 lb.)

Length of spring at valve open position ... 42.93 mm (1.690 in.)

Use again minimum load at valve open position ... 817 N (183.6 lb.)

Free length after test ... 62.7 mm (2.47 in.)

Outside diameter ... 31.75 mm (1.250 in.)

Spring must not be bent more than ... 2.18 mm (.086 in.)

(2) Height to top of valve guide ... 32.3 ± 0.8 mm (1.27 ± .03 in.)

(3) Diameter of valve stem (new) ... 9.441 ± 0.008 mm (.3717 ± .0003 in.)

Use again minimum diameter of intake and exhaust valve stem ... 9.408 mm (.3704 in.)

7N2271 Exhaust Valve - Do not use again.

Bore in valve guide with guide installed in the head (new) ... 9.487 ± 0.025 mm (.3735 ± .0010 in.)

(4) Diameter of valve head:

Exhaust valve ... 41.81 ± 0.13 mm (1.646 ± .005 in.)

Intake valve ... 44.98 ± 0.13 mm (1.771 ± .005 in.)

(5) Angle of intake valve face ... 29 1/4 ± 1/4°

Angle of exhaust valve face ... 44 1/4 ± 1/4°

(6) Depth of bore in head for valve seat insert (new) ... 13.01 ± 0.38 mm (.512 ± .015 in.)

(7) Diameter of valve seat insert for exhaust valve ... 42.850 ± 0.013 mm (1.6870 ± .0005 in.)

Bore in head for valve seat insert for exhaust valve ... 42.774 ± 0.025 mm (1.6840 ± .0010 in.)

(7) Diameter of valve seat insert for intake valve ... 46.025 ± 0.013 mm (1.8120 ± .0005 in.)

Bore in head for valve seat insert for intake valve ... 45.949 ± 0.025 mm (1.8090 ± .0010 in.)

(8) Angle of face of intake valve seat insert ... 30 1/4 ± 1/2°

Angle of face of exhaust valve seat insert ... 44 3/4 ± 1/2°

(9) Dimension from end of closed valve to machined face of head.

Maximum permissible dimension:

Below (recessed from) machined face ... 1.22 mm (.048 in.)

Above (extended from) machined face ... 0.20 mm (.008 in.)

(10) Outside diameter of the face of the valve seat insert:

Exhaust seat ... 40.41 ± 0.13 mm (1.591 ± .005 in.)

Intake seat ... 44.04 ± 0.13 mm (1.734 ± .005 in.)

(11) "Use again" thickness of valve lip:

Exhaust valve ... 2.03 mm (.080 in.)

Intake valve ... 2.51 mm (.099 in.)

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