Disassembly, Inspection and Assembly
DISASSEMBLY
1. Remove manifolds from cylinder head.
2. Remove rocker shafts with rocker arms.
Bolts should be loosened in two or three steps.
3. Remove camshaft.
^ Before removing camshaft, measure camshaft end play.
4. Remove valve components with Tool.
5. Remove valve oil seal with Tool or suitable tool.
INSPECTION
CYLINDER HEAD DISTORTION
Head surface flatness:
Less than 0.1 mm (0.004 in)
If beyond the specified limit, replace it or resurface it.
Resurfacing limit:
The cylinder head of resurfacing limit is determined by the cylinder block resurfacing in an engine.
Amount of cylinder head resurfacing is "A".
Amount of cylinder block resurfacing is "B".
The maximum limit is as follows:
A + B = 0.2 mm (0.008 in)
After resurfacing cylinder head, check that camshaft rotates freely by hand. If resistance is felt, cylinder head must be replaced.
Nominal cylinder head height:
120.60-120.80 mm (4.7480 - 4.7559 in)
CAMSHAFT VISUAL CHECK
Check camshaft for scratches, seizure and wear.
CAMSHAFT RUNOUT
1. Measure camshaft runout at the center journal.
Runout (Total indicator reading):
Limit 0.1 mm (0.004 in)
2. If it exceeds the limit, replace camshaft.
CAMSHAFT CAM HEIGHT
1. Measure camshaft cam height.
Standard cam height:
Intake
35.933 - 36.123 mm (1.4147 - 1.4222 in)
Exhaust
35.746 - 35.936 mm (1.4073 - 1.4148 in)
Cam wear limit:
0.20 mm (0.0079 in)
2. If wear is beyond the limit, replace camshaft.
CAMSHAFT JOURNAL CLEARANCE
1. Install camshaft bracket and tighten bolts to the specified torque.
2. Measure inner diameter of camshaft bearing.
Standard inner diameter:
42.000 - 42.025 mm (1.6535 - 1.6545 in)
3. Measure outer diameter of camshaft journal.
Standard outer diameter:
41.935 - 41.955 mm (1.6510 - 1.6518 in)
4. If clearance exceeds the limit, replace camshaft and/or cylinder head.
Camshaft journal clearance limit:
0.15 mm (0.0059 in)
CAMSHAFT END PLAY
1. Install following parts in cylinder head.
^ Camshaft
^ Camshaft locate plate
^ Distributor
2. Measure camshaft end play.
Camshaft end play:
Standard
0.030 - 0.130 mm (0.0012 - 0.0051 in)
Limit 0.20 mm (0.0079 in)
CAMSHAFT SPROCKET RUNOUT
1. Install sprocket on camshaft.
2. Measure camshaft sprocket runout.
Runout (Total indicator reading):
Limit 0.25 mm (0.0098 in)
3. If it exceeds the limit, replace camshaft sprocket.
VALVE GUIDE CLEARANCE
1. Measure valve deflection in a right-angled direction with camshaft. (Valve and valve guide mostly wear in this direction.)
Valve deflection limit (Dial gauge reading):
0.2 mm (0.008 in)
2. If it exceeds the limit check valve to valve guide clearance.
a. Measure valve stem diameter and valve guide inner diameter.
b. Check that clearance is within specification.
Valve to valve guide clearance limit:
0.1 mm (0.004 in)
c. If it exceeds the limit, replace valve or valve guide.
VALVE GUIDE REPLACEMENT
1. To remove valve guide, heat cylinder head to 110 to 120°C (230 to 248°F).
2. Drive out valve guide with a press [under a 20 kN (2 t, 2.2 US ton 2.0 Imp ton) pressure] or hammer and Tool or suitable tool.
3. Ream cylinder head valve guide hole.
Valve guide hole diameter (for service parts):
Intake
10.185 - 10.196 mm (0.4010 - 0.4014 in)
Exhaust
10.785 - 10.796 mm (0.4246 - 0.4250 in)
4. Heat cylinder head to 110 to 120°C (230 to 248°F) and press service valve guide onto cylinder head.
Projection "L":
Intake
13.2- 13.4 mm (0.520 - 0.528 in)
Exhaust
14.7 - 14.9 mm (0.579 - 0.587 in)
5. Ream valve guide.
Finished size:
Intake
6.000 - 6.015 mm (0.2362 - 0.2368 in)
Exhaust
6.600 - 6.615 mm (0.2598 - 0.2604 in)
VALVE SEATS
Check valve seats for any evidence of pitting at valve contact surface, and reseat or replace if it has worn out excessively.
^ Before repairing valve seats, check valve and valve guide for wear. If they have worn, replace them. Then correct valve seat.
^ Cut with both hands to uniform the cutting surface.
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 in)]:
Intake
30.500 - 30.516 mm (1.2008 - 1.2014 in)
Exhaust
34.300 - 34.316 mm (1.3504 - 1.3510 in)
Reaming should be done to the concentric circles to valve guide center so that valve seat will have the correct fit.
3. Heal cylinder head to 110 to 120°C (230 to 248°F).
4. Press fit valve seat until it seats on the bottom.
5. Cut or grind valve seat using suitable tool at the specified dimensions as shown in Specifications.
6. After cutting, lap valve seat with abrasive compound.
7. Check valve seating condition.
Seat face angle:
44° 45" - 45° 15' deg.
Contacting width "W":
Intake 1.5 mm (0.059 in)
Exhaust 1.8 mm (0.071 in)
VALVE DIMENSIONS
Check dimensions in each valve. For dimensions, refer to Specifications. When valve head has been worn down to 0.5 mm (0.020 in) in margin
thickness, replace valve.
Grinding allowance for valve stem tip is 0.2 mm (0.008 in) or less.
VALVE SPRING
Squareness
1. Measure "S" dimension.
Out-of-square:
Intake
Less than 2.3 mm (0.091 in)
Exhaust
Less than 2.4 mm (0.094 in)
2. If it exceeds the limit, replace spring.
Pressure
Check valve spring pressure.
Pressure: N (kg, lb) at height mm (in)
Standard:
Intake
489.4 (49.9,110.0) at 33.8 (1.331)
Exhaust
545.3 (55.6,122.6) at 34.2 (1.346)
Limit:
Intake
More than 436.4 (44~5, 98.1) at 33.8 (1.331)
Exhaust
More than 486.4 (49.6,109.4) at 34.2 (1.346)
If it exceeds the limit, replace spring.
ROCKER SHAFT AND ROCKER ARM
1. Check rocker shafts for scratches, seizure and wear.
2. Check outer diameter of rocker shaft.
Diameter:
21.979 - 22.000 mm (0.8653 - 0.8661 in)
3. Check inner diameter of rocker arm.
Diameter:
22.023 - 22.043 mm (0.8670 - 0.8678 in)
Rocker arm to shaft clearance:
0.023- 0.064 mm (0.0009 - 0.0025 in)
^ Keep rocker arm with hydraulic valve lifter standing to prevent air from entering hydraulic valve lifter when checking.
ASSEMBLY
1. Install valve component parts.
^ Always use new valve oil seal. Refer to OIL SEAL REPLACEMENT.
^ Before installing valve oil seal, install valve spring seat.
^ Install uneven pitch type spring with its narrow pitch side (painted 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 camshaft and camshaft locate plate.
3. Install rocker shaft with rocker arms.
^ Tighten bolts gradually in two or three stages outwardly from center position.
^ Front mark is punched on front end face of rocker shaft.
^ Tighten rocker shaft bolts after installing timing chain. Set No. 1 cylinder at T.D.C. on compression stroke and tighten bolts corresponding to No. 1 and No.2 rocker shaft bolts; next, set No.4 cylinder at T.D.C. on compression stroke and tighten bolts corresponding to No. 3 and No. 4 bolts. (If camshaft is lifted, rocker shaft bolts will not be equally tightened because of spring tension.)
4. Install manifolds.
INSTALLATION
1. Set No. 1 piston at T.D.C. on its compression stroke as follows:
(1) Align mark on crankshaft pulley with pointer and confirm that distributor rotor head is set as shown in image.
(2) Confirm that knock pin on camshaft is set at the top.
2. Install cylinder head with new gasket and tighten cylinder head bolts in numerical order.
^ Do not rotate crankshaft and camshaft separately, or valves will hit piston heads.
Tightening procedure.
a. Tighten all bolts to 29 N.m (3.0 kg-m, 22 ft-lb).
b. Tighten all bolts to 64 N.m (6.5 kg-m, 47 ft-lb).
c. Loosen all bolts completely.
d. Tighten all bolts to 29 N.m (3.0 kg-m, 22 ft-lb).
e. Turn bolt (1) 80 to 85 degrees clockwise and turn other bolts (2-10) 60 to 65 degrees clockwise. If angle wrench is not available, tighten all bolts to 59 to 69 N.m (6.0 to 7.0 kg-m, 43 to 51 ft-lb).
f. Tighten bolts (11-15) 6.3 to 8.3 N.m (0.64 to 0.85 kg-m, 4.6 to 6.1 ft-lb).
^ Two different lengths of cylinder head bolts are used. Do not confuse one length type with the other during installation.
3. Set chain on camshaft sprocket by aligning each mating mark. Then install camshaft sprocket to camshaft.
4. Check hydraulic valve lifter.
(1) Push hydraulic valve lifter forcefully with your finger.
^ Be sure to check it with rocker arm in its free position (not on the lobe).
(2) If valve lifter moves more than 1 mm (0.04 in), air may be inside of it.
(3) Bleed air off by running engine at 1,000 rpm under no-load for about 10 minutes.
(4) If hydraulic valve lifters are still noisy, replace them and bleed air off again in the same manner as in step (3).