3126B Marine Engine Caterpillar

Illustration 1	g01383868

Note: The inlet and exhaust valve stems must be coated with engine oil prior to installation in the cylinder head.

Note: The tips of the inlet and exhaust valves must be coated with 8T-2998 Lubricant . The lubricant must be applied after assembly of the retainer.

(1) Exhaust valve

(2) Inlet valve

(3) 137-6718 Spring for exhaust valve

Free length ... 92.08 mm (3.625 inch)

Assembled length ... 80.27 mm (3.160 inch)

Load at assembled length ... 662 ± 33 N (148 ± 7 lb)

Minimum operating length ... 66.27 mm (2.609 inch)

Load at minimum operating length ... 1445 ± 58 N (325 ± 13 lb)

(4) 140-6188 Spring for inlet valve

Free length ... 67.5 mm (2.66 inch)

Assembled length ... 60.4 mm (2.38 inch)

Load at assembled length ... 302.5 ± 18 N (68.01 ± 4 lb)

Minimum operating length ... 46.4 mm (1.83 inch)

Load at minimum operating length ... 899 ± 36 N (202 ± 8 lb)

(A) Height to the top of the valve guides

Inlet valves ... 23.00 ± 0.50 mm (0.906 ± 0.020 inch)

Exhaust valves ... 17.80 ± 0.50 mm (0.701 ± 0.020 inch)

Diameter of inlet valve guide ... 13.030 ± 0.008 mm (0.5130 ± 0.0003 inch)

Diameter of exhaust valve guide ... 16.000 ± 0.008 mm (0.6299 ± 0.0003 inch)

Note: Install the valve guide from the spring side of the cylinder head.

Note: Assemble the valve guide. Seat the seal against the top of the valve guide.

(B) Valve stem diameter ( new)

Inlet valves ... 8.000 ± 0.008 mm (0.3150 ± 0.0003 inch)

Exhaust valve ... 9.441 ± 0.010 mm (0.3717 ± 0.0004 inch)

After installation into the cylinder head, the valve guide bore is the following value.

Diameter of the valve guide bore ( new)

Inlet valve ... 8.072 ± 0.013 mm (0.3178 ± 0.0005 inch)

Exhaust valve ... 9.512 ± 0.013 mm (0.3745 ± 0.0005 inch)

(C) Diameter of the valve head

Inlet valve ... 40.00 ± 0.13 mm (1.575 ± 0.005 inch)

Exhaust valve ... 43.00 ± 0.13 mm (1.693 ± 0.005 inch)

(D) Angle of the valve faces

Inlet valve ... 29.75 ± 0.25 degrees

Exhaust valve ... 45 ± 0.25 degrees

Illustration 2	g01383885

(E) Diameter of the valve seat inserts

Inlet valve ... 42.000 ± 0.013 mm (1.6535 ± 0.0005 inch)

Exhaust valve ... 46.000 ± 0.013 mm (1.8110 ± 0.0005 inch)

Diameter of the bore in cylinder head for the valve seat insert

Bore diameter

Inlet valve ... 41.931 ± 0.013 mm (1.6508 ± 0.0005 inch)

Exhaust valve ... 45.931 ± 0.013 mm (1.8083 ± 0.0005 inch)

Note: Reduce the temperature of the valve seat insert in order to shrink the valve seat insert. Install the valve seat insert in the head.

(F) Angle of the valve seat inserts

Inlet valve ... 30.25 ± 0.25 degrees

Exhaust valve ... 45.5 ± 0.25 degrees

(G) Depth of the bore in the head for the valve seat insert

Intake valve ... 9.0 ± 0.05 mm (0.3543 ± 0.002 inch)

Exhaust valve ... 10.00 ± 0.05 mm (0.394 ± 0.002 inch)

(H) Inside diameter of the seating face of the valve seat insert

Inlet valve ... 37.351 mm (1.4705 inch)

Exhaust valve ... 40.800 mm (1.6063 inch)

Note: Do not reuse the valve seat inserts if the outside diameter of the valve seat insert is larger than the specified value.