3412 Generator Set Engines Caterpillar

Illustration 1	g00706923

(1) Bore in the rocker arm for the rocker arm shaft ... 24.803 ± 0.013 mm (0.9765 ± 0.0005 inch)

Diameter of new rocker arm shaft ... 24.752 ± 0.013 mm (0.9745 ± 0.0005 inch)

(2) Refer to Specifications, "Cylinder Head" for information that is related to the tightening sequence of the cylinder head bolts.

(3) Tighten the valve adjustment screw locknut after you set the valve lash.

Torque for the adjustment locknut ... 47 ± 9 N·m (35 ± 7 lb ft)

Inlet valve lash (4) ... 0.38 ± 0.10 mm (0.015 ± 0.004 inch)

Exhaust valve lash (4) ... 0.76 ± 0.10 mm (0.030 ± 0.004 inch)

(5) Diameter of new valve lifter ... 27.896 ± 0.013 mm (1.0983 ± 0.0005 inch)

Diameter of the valve lifter bore that is in the cylinder block ... 27.953 ± 0.019 mm (1.1005 ± 0.0007 inch)

(4) 6N-6872 Guide Spring

Refer to Guideline for Reusable Parts, SEBF8069, "Salvage of Lifter Bores in 3400 Family Engines" for information that is related to reconditioning the valve lifter bores.

Illustration 2	g00706960

(7) 2N-7229 Spring

Length under test force ... 74.2 mm (2.92 inch)

Test force ... 45 to 53 N (10 to 12 lb)

Free length after test ... 114.3 mm (4.50 inch)

Outside diameter ... 29.7 mm (1.17 inch)

(8) The protrusion of the dowel above the top surface of the rocker shaft support is the following value. ... 9.7 ± 1.0 mm (0.38 ± 0.04 inch)

(9) Clearance for the rocker arms ... 0.30 to 1.40 mm (0.012 ± 0.055 inch)

(10) Add or remove 2N-7228 Washers in order to adjust clearance (9).