Disassembly and Assembly

CAUTION: When installing sliding parts such as rocker arms, camshaft and oil seal, be sure to apply new engine oil on their sliding surfaces.
When tightening cylinder head bolts and rocker shaft bolts, apply new engine oil to thread portions and seat surfaces of bolts.
If hydraulic valve lifter is kept on its side, there is a risk of air entering it. After removal, always set hydraulic valve lifter straight up, or when laying it on its side, have it soak in new engine oil.
Do not disassemble hydraulic valve lifter.
Attach tags to valve lifters so as not to mix them up.









Disassembly
1. Remove exhaust manifolds from cylinder head.






2. Remove rocker shafts with rocker arms.
Bolts should be loosened in two or three steps.

3. Remove hydraulic valve lifters and lifter guide. Hold hydraulic valve lifters with wire so that they will not drop from lifter guide.
4. Remove oil seal and camshaft.
Before removing camshaft, measure camshaft end play.






5. Remove valve components with Tool.
6. Remove valve oil seals with Tool or suitable tool.






VALVE GUIDE REPLACEMENT
1. To remove valve guide, heat cylinder head to 150 to 160°C (302 to 320°F) by soaking in heated oil.






2. Drive out valve guide with a press [under a 20 kN (2 ton, 2.2 US ton, 2.0 Imp ton) pressure] or hammer and suitable tool.






3. Ream cylinder head valve guide hole.

Valve guide hole diameter (for service parts):
Intake:.....11.175 - 11.196 mm (0.4400 - 0.4408 inch)
Exhaust:.....12.175 - 12.196 mm (0.4793 - 0.4802 inch)






4. Heat cylinder head to 150 to 160°C (302 to 320°F) and press service valve guide onto cylinder head.

Projection "L":.....13.2 - 13.4 mm (0.520 - 0.528 inch)

5. Ream valve guide.

Finished size:
Intake:.....7.000 - 7.018 mm (0.2756 - 0.2763 inch)
Exhaust:.....8.000 - 8.011 mm (0.3150 - 0.3154 inch)







REPLACING VALVE SEAT FOR SERVICE PARTS
1. Bore out old seat until it collapses. The machine depth stop should be set so that boring cannot continue beyond the bottom face of the seat recess in cylinder head.
2. Ream cylinder head recess.

Reaming bore for service valve seat:
Oversize.....[0.5 mm (0.020 inch)]:
Intake:.....44.500 - 44.516 mm (1.7520 - 1.7526 inch)
Exhaust:......37.500 - 37.516 mm (1.4764 - 1.4770 inch)

Reaming should be done in circles concentric to the valve guide center so that valve seat will have the correct fit.

3. Heat cylinder head to 150 to 160°C (302 to 320°F) by soaking in heated oil.
4. Press fit valve seat until it seats on the bottom.






5. Cut or grind valve seat using suitable tool at the specified dimensions to specification. Refer to Engine; Specifications; Mechanical
6. After cutting, lap valve seat with abrasive compound.






7. Check valve seating condition.





8. Use a depth gauge to measure the distance between the mounting surface of the cylinder head spring seat and the valve stem end. If the distance is shorter than specified, repeat step 5 above to adjust it. If it is longer, replace the valve seat with a new one.

Intake:.....44.7 - 44.9 mm (1.760 - 1.768 inch)
Exhaust:.....45.4 - 45.6 mm (1.787 - 1.795 inch)



Assembly
1. Install valve component parts.
- Always use new valve oil seal.
- Before installing valve oil seal, install inner valve spring seat.






- Install outer valve spring (uneven pitch type) with its narrow pitch side toward cylinder head side.
- After installing valve component parts, use plastic hammer to lightly tap valve stem tip to assure a proper fit.






2. Install camshafts, locate plates and cylinder head rear covers.
Set knock pin of camshaft at the top.






3. Install valve lifters into valve lifter guide.
- Assemble valve lifters to their original position and hold all valve lifters with wire to prevent lifters from falling off.
- After installing, remove the wire.






4. Install rocker shafts with rocker arms.
Tighten bolts gradually in two or three stages.
Before tightening, be sure to set camshaft the lobe at the position where lobe is not lifted.

a. Set No. 1 piston at TDC on its compression stroke and tighten rocker shaft bolts for No. 2, No. 4 and No. 6 cylinders.
b. Set No. 4 piston at TDC on its compression stroke and tighten rocker shaft bolts for No. 1, No. 3 and No. 5 cylinders.

5. Install exhaust manifold to cylinder head in reverse order of removal.