Service Limits & General Specifications
Inspection After DisassemblyCYLINDER HEAD DISTORTION
1. Remove any oil, scale, gasket, sealant and carbon deposits from the cylinder head surface.
CAUTION: Do not allow any debris to enter the oil or coolant passages.
2. Measure the bottom surface of the cylinder head for distortion in six directions as shown, using suitable tools.
Standard: 0.03 mm (0.0012 inch)
Limit: 0.1 mm (0.004 inch)
^ If measurement exceeds the limit, replace the cylinder head.
VALVE DIMENSIONS
^ Check the dimensions of each valve. Refer to "VALVE DIMENSIONS".
^ If dimensions are out of the standard, replace valve.
VALVE GUIDE CLEARANCE
Valve Stem Diameter
Measure diameter of valve stem using suitable tool.
Standard
Intake: 5.965 - 5.980 mm (0.2348 - 0.2354 inch)
Exhaust: 5.955 - 5.970 mm (0.2344 - 0.2350 inch)
Valve Guide Inside Diameter
Measure inside diameter of valve guide using suitable tool.
Standard
Intake and Exhaust: 6.000 - 6.018 mm (0.2362 - 0.2369 inch)
Valve Guide Clearance
^ (Valve guide clearance) = (Valve guide inside diameter) - (Valve stem diameter).
Valve guide clearance:
Standard
Intake: 0.020 - 0.053 mm (0.0008 - 0.0021 inch)
Exhaust: 0.030 - 0.063 mm (0.0012 - 0.0025 inch)
Limit
Intake: 0.08 mm (0.0031 inch)
Exhaust: 0.09 mm (0.0035 inch)
^ If the calculated value exceeds the limit, replace valve and/or valve guide. When the valve guide must be replaced, refer to "VALVE GUIDE REPLACEMENT".
VALVE GUIDE REPLACEMENT
When valve guide is removed, replace with oversized (0.2 mm, 0.008 inch) valve guide.
1. To remove valve guide, heat cylinder head to 110° to 130°C (230°to 266°F) by soaking in heated oil.
2. Remove the valve guide using suitable tool.
CAUTION: Cylinder head contains heat. When working, wear protective equipment to avoid getting burned.
3. Ream cylinder head valve guide hole using suitable tool.
Valve guide hole diameter:
Standard
Intake and exhaust: 9.975 - 9.996 mm (0.3927 - 0.3935 inch)
Oversize (service)
Intake and exhaust: 10.175 - 10.196 mm (0.4006 - 0.4014 inch)
4. Heat cylinder head to 110 to 130°C (230 to 266°F) by soaking in heated oil.
5. Press valve guide from camshaft side to dimensions as shown.
CAUTION: Cylinder head contains heat. When working, wear protective equipment to avoid getting burned.
6. Ream cylinder head valve guide hole using suitable tool.
Valve guide hole diameter:
Intake and exhaust: 6.000 - 6.018 mm (0.2362 - 0.2369 inch)
VALVE SEAT CONTACT
^ After confirming that the dimensions of valve guides and valves are within specifications, perform this procedure.
^ Apply Prussian blue (or white lead) onto contacting surface of valve seat to check the condition of the valve contact on the surface.
^ Check if the contact area band is continuous all around the circumference.
^ If not, grind to adjust valve fitting and check again. If the contacting surface still has NO conditions even after the re-check, replace valve seat.
VALVE SEAT REPLACEMENT
When valve seat is removed, replace with oversized (0.5 mm, 0.020 inch) valve seat.
1. Bore out old seat until it collapses. Boring should not continue beyond the bottom face of the seat recess in cylinder head. Set the machine depth stop to ensure this.
2. Ream cylinder head recess diameter for service valve seat.
Oversize [0.5 mm (0.020 inch)] (Service):
Intake: 38.500 - 38.516 mm (1.5157 - 1.5164 inch)
Exhaust: 32.700 - 32.716 mm (1.2874 - 1.2880 inch)
^ Be sure to ream in circles concentric to the valve guide center.
^ This will enable valve seat to fit correctly.
3. Heat cylinder head to 110 to 130°C (230 to 266°F) by soaking in heated oil.
4. Cool the valve seats well with dry ice. Force fit the valve seat into the cylinder head.
CAUTION:
^ Avoid directly touching cold valve seats.
^ Cylinder head contains heat. When working, wear protective equipment to avoid getting burned.
5. Finish the seat to the specified dimensions using suitable tool. Refer to "Valve Seat".
CAUTION: When using valve seat cutter, firmly grip the cutter handle with both hands. Then, press on the contacting surface all around the circumference to cut in a single drive. Improper pressure on with the cutter or cutting many different times may result in stage valve seat.
6. Grind to obtain the dimensions indicated as shown.
^ Using compound, grind to adjust valve fitting.
7. Check again for normal contact. Refer to "VALVE SEAT CONTACT".
VALVE SPRING SQUARENESS
^ Set try square along the side of valve spring and rotate the spring. Measure the maximum clearance between the top face of spring and try square.
Limit : Less than 2.2 mm (0.087 inch)
^ If measurement is not within specifications, replace the valve spring.
VALVE SPRING DIMENSIONS AND VALVE SPRING PRESSURE LOAD
^ Check the valve spring pressure at the specified spring height.
Standard:
Intake and exhaust
Free height: 50.58 mm (1.9913 inch)
Installation height: 37.0 mm (1.457 inch)
Installation load: 165.8 - 187.0 N (16.9 - 19.1 kg, 37 - 42 lbs.)
Height during valve open: 28.2 mm (1.110 inch)
Load with valve open: 314.8 - 355.0 N (32.1 - 36.2 kg, 71 - 80 lbs.)
^ If measurement is not within specifications, replace the valve spring.
Cylinder Head Bolts Diameter
^ Cylinder head bolts are tightened by plastic zone tightening method. Whenever the size difference between d1 and d2 exceeds the limit, replace the bolt with a new one. Limit (d1 - d2) 0.18 mm (0.0071 inch)
^ If reduction of diameter appears in a position other than d2, use it as d2 point.
CYLINDER HEAD