Inspection
INSPECTION
CYLINDER HEAD
1. Check the cylinder head gasket surface for flatness by using a straight edge and feeler gauge.
Standard value: Less than 0.03 mm (0.001 inch)
Limit: 0.2 mm (0.007 inch)
2. If it exceeds the limit, correct to meet specification.
Grinding limit: *0.2 mm (0.007 inch)
* Includes combined with cylinder block grinding.
Cylinder head height (Specification when new):
120 mm (4.7 inches)
VALVE
1. Check the valve seat contact. Valve seat contact should be uniform at the center of the valve face. If incorrect, reface using a valve refacer.
2. If the margin is below the limit, replace the valve.
Standard value:
[Intake] 1.0 mm (0.03 inch)
[Exhaust] 1.2 mm (0.04 inch)
Minimum limit:
[Intake] 0.5 mm (0.02 inch)
[Exhaust] 0.7 mm (0.03 inch)
3. Measure the valve's total length. If the measurement is less than the limit, replace the valve.
Standard value:
[Intake] 111.33 mm (4.383 inches)
[Exhaust] 113.54 mm (4.470 inches)
Minimum limit:
[Intake] 110.83 mm (4.363 inches)
[Exhaust] 113.04 mm (4.450 inches)
VALVE SPRING
1. Measure the free height of the spring. If it is less than the limit, replace.
Standard value:
[Intake] 54.8 mm (2.16 inches)
[Exhaust] 56.1 mm (2.21 inches)
Minimum limit:
[Intake] 53.8 mm (2.12 inches)
[Exhaust] 55.1 mm (2.17 inches)
2. Measure the squareness of the spring. If it exceeds the limit, replace.
Standard value: 2 degrees or less
Limit: 4 degrees
VALVE GUIDE
Measure the clearance between the valve guide and valve stem. If it exceeds the limit, replace the valve guide or valve, or both.
Standard value:
[Intake] 0.020 - 0.047 mm (0.0008 - 0.0019 inch)
[Exhaust] 0.035 - 0.062 mm (0.0014 - 0.0024 inch)
Limit:
[Intake] 0.10 mm (0.003 inch)
[Exhaust] 0.15 mm (0.005 inch)
VALVE SEAT
Assemble the valve, then measure the contact width. If the measurement exceeds the specified limit, replace the valve seat.
Standard value: 0.9 - 1.3 mm (0.04 - 0.05 inch)
CAUTION:
If the variation in the width exceeds 0.2 mm (0.008 inch) even if the contact width is within the standard value, replace or correct the valve seat.
VALVE SEAT RECONDITIONING PROCEDURE
1. Before correcting the valve seat, check for clearance between the valve guide and valve and, if necessary, replace the valve guide.
2. Using the seat grinder, correct to obtain the specified seat width and angle.
3. After correcting the valve seat, lap the valve and valve seat using lapping compound.
Then, check the valve stem projection.
VALVE SEAT REPLACEMENT PROCEDURE
1. Cut the valve seat from the inside to thin the wall thickness. Then, remove the valve seat.
2. Rebore the valve seat hole in the cylinder head to a selected oversize valve seat diameter.
Intake seat ring hole diameters
0.3 oversize:
35.30 - 35.33 mm (1.3898 - 1.3909 inches)
0.6 oversize:
35.60 - 35.63 mm (1.4016 - 1.4028 inches)
Exhaust seat ring hole diameters
0.3 oversize:
33.30 - 33.33 mm (1.3110 - 1.3122 inches)
0.6 oversize:
33.60 - 33.63 mm (1.3228 - 1.3240 inches)
3. Before fitting the valve seat, either heat the cylinder head up to approximately 250°C
(482°F) or cool the valve seat in liquid nitrogen, to prevent the cylinder head bore from galling.
4. Using a valve seat cutter, correct the valve seat to the specified width and angle.
See "VALVE SEAT RECONDITIONING PROCEDURE".
VALVE GUIDE REPLACEMENT PROCEDURE
1. Using a press, remove the valve guide toward the cylinder block.
2.
CAUTION:
Do not install a valve guide of the same size again.
Rebore the valve guide hole of the cylinder head so that it fits the press-fitted oversize valve guide.
Valve guide hole diameters
0.05 oversize 11.05 - 11.07 mm (0.4350 - 0.4358 inch)
0.25 oversize 11.25 - 11.27 mm (0.4429 - 0.4437 inch)
0.50 oversize 11.50 - 11.52 mm (0.4528 - 0.4535 inch)
3. Press-fit the valve guide until it protrudes 14.0 mm (0.55 inch) from the cylinder head top surface as shown in the illustration.
NOTE:
When press-fitting the valve guide, work from the cylinder head top surface.
NOTE:
Pay attention to the difference in length of the valve guides. [Intake side:
45.5 mm (1.79 inches);
exhaust side: 50.5 mm (1.99 inches)]
NOTE:
After installing the valve guides, insert new valves in them to check for smooth operation.