Inspect for flatness.
Using a precision straight edge and feeler gauge, measure the surface contacting cylinder block and the manifolds for warpage.
Flatness of cylinder head gasket surface
Standard : Less than 0.05 mm (0.002 in.)
[Less than 0.02 mm (0.0008 in.) / 150x150]
Flatness of manifold gasket surface
Standard : Less than 0.03 mm (0.001 in) / 110x110
Inspect for cracks.
Check the combustion chamber, intake ports, exhaust ports and cylinder block surface for cracks. If cracked, replace the cylinder head.
Inspect valve stems and valve guides.
Using a caliper gauge, measure the inside diameter of the valve guide.
Valve guide I.D.
Intake / Exhaust : 5.500 ~ 5.512 mm (0.216 ~ 0.217 in.)
Using a micrometer, measure the diameter of the valve stem.
Valve stem O.D.
Intake : 5.465 ~ 5.480 mm (0.2151 ~ 0.2157 in.)
Exhaust : 5.458 ~ 5.470 mm (0.2149 ~ 0.2153 in.)
Subtract the valve stem diameter measurement from the valve guide inside diameter measurement.
Valve stem-to-guide clearance
[Standard]
Intake : 0.020 ~ 0.047 mm (0.0008 ~ 0.0018 in.)
Exhaust : 0.030 ~ 0.054 mm (0.0012 ~ 0.0021 in.)
[Limit]
Intake : 0.07 mm (0.0027 in.)
Exhaust : 0.09 mm (0.0035 in.)
Inspect valves.
Check the valve is ground to the correct valve face angle.
Check that the surface of the valve for wear.
If the valve face is worn, replace the valve.
Check the valve head margin thickness.
If the margin thickness is less than minimum, replace the valve.
Margin
[Standard]
Intake : 1.56 ~ 1.86 mm (0.06142 ~ 0.07323 in.)
Exhaust (Leaded type) :
1.93 ~ 2.23 mm (0.07598 ~ 0.08779 in.)
Exhaust (Unleaded type) :
1.73 ~ 2.03 mm (0.06811 ~ 0.07992 in.)
Check the valve length.
Length
Intake : 105.27 mm (4.1445 in)
Exhaust (Leaded type) : 105.70 mm (4.1614 in.)
Exhaust (Unleaded type) : 105.50 mm (4.1535 in.)
Check the surface of the valve stem tip for wear.
If the valve stem tip is worn, replace the valve.
Inspect valve seats
Check the valve seat for evidence of overheating and improper contact with the valve face.
If the valve seat is worn, replace cylinder head.
Before reconditioning the seat, check the valve guide for wear. If the valve guide is worn, replace cylinder head.
Recondition the valve seat with a valve seat grinder or cutter.
The valve seat contact width should be within specifications and centered on the valve face.
Inspect valve springs.
Using a steel square, measure the out-of-square of the valve spring.
Using vernier calipers, measure the free length of the valve spring.
Valve spring
[Standard]
Free height : 45.5 mm (1.7913 in.)
Out-of-square : 1.5˚
Inspect MLAs.
Using a micrometer, measure the MLA outside diameter.
MLA O.D.
Intake/Exhaust :
34.964 ~ 34.980 mm (1.3765 ~ 1.3771 in.)
Using a caliper gauge, measure MLA tappet bore inner diameter of cylinder head.
Tappet bore I.D.
Intake/Exhaust :
35.000 ~ 35.025 mm (1.3779 ~ 1.3789 in.)
Subtract MLA outside diameter measurement from tappet bore inside diameter measurement.
MLA to tappet bore clearance
[Standard]
Intake/Exhaust :
0.020 ~ 0.061 mm (0.0008 ~ 0.0024 in.)
[Limit]
Intake/Exhaust : 0.07 mm (0.0027 in.)
