Inspection and Replacement

INSPECTION





1. INSPECT CYLINDER HEAD FOR FLATNESS
(a) Using a precision straight edge and a feeler gauge, measure the surface contacting the cylinder block and the manifolds for warpage.

Maximum Warpage:

If the warpage is greater than the maximum, replace the cylinder head.





2. INSPECT CYLINDER HEAD FOR CRACKS
(a) Using a dye penetrant, check the intake ports, exhaust ports and cylinder surface for cracks.
If cracked, replace the cylinder head.





3. INSPECT VALVE SEATS
(a) Apply a light coat of Prussian blue to the valve face.
(b) Lightly press the valve face against the valve seat.
(c) Check the valve face and valve seat according to the following procedure:
(1) If Prussian blue appears 360° around the valve face, the valve face is concentric. If not, replace the valve.
(2) If Prussian blue appears 360° around the valve seat, the guide and valve face are concentric. If not, resurface the valve seat.
(3) Check that the valve seat contact is in the middle of the valve face with the width between 1.0 to 1.4 mm (Intake side (0.039 to 0.055 inch)).
(4) Check that the valve seat contact is in the middle of the valve face with the width between 1.2 to 1.6 mm (Exhaust side (0.047 to 0.063 inch)).
4. REPAIR VALVE SEATS

NOTICE:
- Repair the seat while checking the seating position.
- Keep the lip free from foreign matter.





(a) Using a 45° cutter, resurface the valve seat so that the valve seat width is more than the specification.





(b) Using 30° and 75° cutters, correct the valve seat so that the valve contacts the entire circumference of the seat. The contact should be in the center of the valve seat, and the valve seat width should be maintained within the specified range around the entire circumference of the seat.

Valve Seat Width:

(c) Hand rub the valve and valve seat with an abrasive compound.
(d) Check the valve seating position.
5. INSPECT CAMSHAFT THRUST CLEARANCE
(a) Install the camshafts.





(b) Using a dial indicator, measure the thrust clearance while moving the camshaft back and forth.

Standard Thrust Clearance:

Maximum Thrust Clearance:

If the thrust clearance is greater than the maximum, replace the cylinder head. If the thrust surface is damaged, replace the camshaft.
6. INSPECT CAMSHAFT OIL CLEARANCE
(a) Clean the bearing caps and camshaft journals.
(b) Place the camshafts on the cylinder head.





(c) Lay a strip of Plastigage across each of the camshaft journals.
(d) Install the bearing caps.

NOTICE: Do not turn the camshaft.

(e) Remove the bearing caps.





(f) Measure the Plastigage at its widest point.

Standard Oil Clearance:

Maximum Oil Clearance:

NOTICE:
- Completely remove the Plastigage after the inspection.
- If the oil clearance is greater than the maximum, replace the camshaft. If necessary, replace the cylinder head.
- If the oil clearance on the camshaft No. 1 journal is greater than the maximum, choose a new bearing and install it.





(1) Check the number mark shown in the illustration.

Cylinder Head Journal Bore Diameter:

Standard Bearing Center Wall Thickness:

Camshaft Journal Diameter:

7. INSPECT INNER COMPRESSION SPRING
(a) Using vernier calipers, measure the free length of the valve spring.
Free length: 47.43 mm (1.867 inch)
If the free length is not as specified, replace the valve spring.





(b) Using steel squares, measure the deviation of the valve spring.
Maximum deviation: 1.6 mm (0.063 inch)
If the deviation is greater than the maximum, replace the valve spring.





8. INSPECT INTAKE VALVE
(a) Using a gasket scraper, scrape off any carbon on the valve head.





(b) Using vernier calipers, measure the overall length of the valve.
Standard overall length: 101.71 mm (4.0043 inch)
Minimum overall length: 101.21 mm (3.9846 inch)
If the overall length is less than the minimum, replace the valve.





(c) Using a micrometer, measure the diameter of the valve stem.
Valve stem diameter: 5.470 to 5.485 mm (0.2154 to 0.2159 inch)
If the valve stem is not as specified, check the oil clearance.





(d) Using vernier calipers, measure the valve head margin thickness.
Standard margin thickness: 1.05 to 1.45 mm (0.0413 to 0.0571 inch)
Minimum margin thickness: 0.50 mm (0.0197 inch)
If the margin thickness is less than the minimum, replace the valve.





9. INSPECT EXHAUST VALVE
(a) Using a gasket scraper, scrape off any carbon on the valve head.





(b) Using vernier calipers, measure the overall length of the valve.
Standard overall length: 101.15 mm (3.9823 inch)
Minimum overall length: 100.70 mm (3.9646 inch)
If the overall length is less than the minimum, replace the valve.





(c) Using a micrometer, measure the diameter of the valve stem.
Valve stem diameter: 5.465 to 5.480 mm (0.2152 to 0.2157 inch)
If the valve stem is not as specified, check the oil clearance.





(d) Using vernier calipers, measure the valve head margin thickness.
Standard margin thickness: 1.20 to 1.60 mm (0.0472 to 0.0630 inch)
Minimum margin thickness: 0.50 mm (0.0197 inch)
If the margin thickness is less than the minimum, replace the valve.





10. INSPECT INTAKE VALVE GUIDE BUSH
(a) Using a caliper gauge, measure the inside diameter of the guide bush.
Bushing inside diameter: 5.510 to 5.530 mm (0.2169 to 0.2177 inch)
(b) Subtract the valve stem diameter measurement from the guide bush inside diameter measurement.
Standard oil clearance: 0.025 to 0.060 mm (0.0010 to 0.0024 inch)
Maximum oil clearance: 0.080 mm (0.0031 inch)
If the clearance is greater than the maximum, replace the valve and guide bush.





11. INSPECT EXHAUST VALVE GUIDE BUSH
(a) Using a caliper gauge, measure the inside diameter of the guide bush.
Bushing inside diameter: 5.510 to 5.530 mm (0.2169 to 0.2177 inch)
(b) Subtract the valve stem diameter measurement from the guide bushing inside diameter measurement.
Standard oil clearance: 0.030 to 0.065 mm (0.0012 to 0.0026 inch)
Maximum oil clearance: 0.100 mm (0.0039 inch)
If the clearance is greater than the maximum, replace the valve and guide bush.





12. INSPECT VALVE LIFTER
(a) Using a micrometer, measure the lifter diameter.
Lifter diameter: 30.966 to 30.976 mm (1.2191 to 1.2195 inch)





(b) Using a caliper gauge, measure the lifter bore diameter of the cylinder head.
Standard lifter bore diameter: 31.009 to 31.025 mm (1.2208 to 1.2215 inch)
(c) Subtract the lifter diameter measurement from the lifter bore diameter measurement.
Standard oil clearance: 0.033 to 0.059 mm (0.0013 to 0.0023 inch)
Maximum oil clearance: 0.070 mm (0.0028 inch)
If the oil clearance is greater than the maximum, replace the lifter. If necessary, replace the cylinder head.





13. INSPECT CYLINDER HEAD SET BOLT
(a) Using vernier calipers, measure the length of the head bolts from the seat to the end.
Standard bolt length: 141.3 to 142.7 mm (5.563 to 5.618 inch)
Maximum bolt length: 144.2 mm (5.677 inch)
If the bolt length is greater than the maximum, replace the cylinder head set bolt.