Note

With engine in chassis, the rear cylinder rocker arm cover and cylinder head must be removed from engine as an assembly. There is not enough clearance between rocker arm cover and frame to remove rocker arm cover only.

DISASSEMBLING CYLINDER HEAD (Fig. 3B-7)

Refer to Fig. 3B-7 and follow the order of disassembly. Free the rocker arm cover (5) from cylinder head by removing cover screws (4). Before further disassembly, carefully check the rocker arm pads and ball sockets for pitting and excessive wear. Also, check the rocker arm shaft (8) for appreciable play in the rocker arm bushings (12). If rocker arm assembly is noticeably worn, disassemble unit for further inspection and replacement of parts.

Remove rocker arm shaft, screw and "O" ring (6), acorn nut and washer (7). Discard shaft screw "O" ring. Tap rocker arm shaft (8) from cover and remove the following parts: Spring (9), rocker arm (10) and spacer (11). Mark rocker arm shaft and arm in some manner so all parts may be returned to respective locations during assembly. Rocker arms are not interchangeable. Exhaust rocker arms have extra oil hole to provide cooling on valve.

Compress valve springs using Valve Spring Compressor, Part No. 96600-36, and remove valve keys (13) from ends of valve stems as shown in Fig. 3B-8. Mark keys (13) to identify them with their respective valves. Remove valve spring collars (14 and 17), springs (15 and 16) and valves (18). It is customary to reassemble valves in same cylinder head from which they were removed; therefore, before removing, mark them in some manner to identify them with front and rear cylinder head.

CLEANING AND INSPECTING (Fig. 3B-7)

Thoroughly clean all parts and inspect them for wear and damage. Clean out oil passages with compressed air.

1. Push rod

2. Cover spring keeper

3. Cover cork washer (3)

4. Lower cover

5. Cover screw washer

6. Cover spring

7. Spring retainer

8. Upper cover

14. Valve spring upper collar (2)

15. Inner valve spring (2)

16. Outer valve spring (2)

17. Valve spring lower collar (2)

18. Intake and exhaust valve

19. Intake and exhaust valve guide

20. Cylinder head

21. Cylinder head gasket

Figure following name of part indicates quantity necessary for one complete assembly.

1. Cylinder head bolt and washer (4)

2. Oil line nut and rubber sleeve (2)

3. Rocker arm cover to crankcase oil line.

4. Rocker arm cover screw and washer

5. Rocker arm cover

6. Rocker arm shaft screw and

7. Rocker arm shaft acorn nut and washer (2 each)

11. Rocker arm spacer (2)

12. Rocker arm bushing (4)

Figure 3B-7. Cylinder Head Assembly - Exploded View

Inspect oil line nut rubber sleeve (2), if damaged or worn, replace when reassembling.

Carefully check the rocker arm (10) and shaft (8) for wear. Replace rocker arm bushings if shaft is over .002 in. loose in bushings. Examine the rocker arm pads. If slightly worn, redress as described in "Repairing Rocker Arm and Bushings." If rocker arm and ball sockets are worn and elongated, the rocker arms must be replaced.

Place cylinder head in "Gunk Hydro-Seal" until deposits are soft. Then clean outside of cylinder head (20) with a wire brush. Scrape carbon from cylinder head combustion chamber, inlet and exhaust valve ports. When scraping carbon, be careful not to scratch or nick cylinder head face, as leakage will result. Blow off loosened carbon and dirt particles and wash head in gasoline or solvent. Force air through all oil holes in cylinder head to make sure passages are clean.

If the valve seat is pitted, burned, corroded or has any indication of improper valve seating, recondition the seat as described in "Refacing Valves and Valve Seats." Replace any valve seat inserts that are cracked or loose in the cylinder head. See "Replacing Valve Seat Inserts."

Check length and tension of each valve spring (15 and 16) using Valve Spring Tester, Part No. 96797-47. Replace spring if 1/8 in. or more shorter than a new spring, or tension shows 5 lbs. below low limit tension of new spring. Refer to, "Engine Specifications," Section 3A, for free length, compressed length and poundage of new valve springs.

Remove carbon from valve head and steiji using a knife and wire wheel - never a file or other hardened tool that will scratch or nick valve. Polish valve stem with fine emery cloth or steel wool. Replace valves that are badly scored, warped or in bent condition. Reface valves that are slightly pitted, burned or in corroded condition as described in "Refacing Valves and Valve Seats."

Clean intake valve guide with a 5/16 in. reamer and exhaust valve guide with a 11/32 in. reamer, and examine for wear and valve stem clearance. Check the valve fit in guide and guide fit in cylinder head. Replace guide, or possibly both valve and guide if either part is not within tolerances, described in "Engine Specifications," Section 3A.

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Figure 3B-8. Valve Spring Compressor Revised: 10-65

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