ENGINE
B2650HSDC, B3350HSDC, WSM
1-S44
[3] SERVICING
(1) Cylinder Head and Valve
Top Clearance
1. Remove the cylinder head.
2. With the piston at TDC, use grease to affix three or four
plastigauges (1) of a diameter 1.5 mm (0.059 in.) × 5.0 to
7.0 mm (0.20 to 0.27 in.) long to the crown of the piston; keep
the gauges away from the intake valve and combustion
chamber fittings.
3. Take the piston to an intermediate position, install the cylinder
head and tighten the head bolts to the specified torque.
4. Turn the crankshaft so the piston goes through TDC.
5. Remove the cylinder head and compare the width of the
crushed plastigauges (2) with the scale.
6. If they are out of spec, check the oil clearance of the crankpin,
journals and piston pins.
• Top clearance = Width of the crushed plastigauge (2).
[D1305-E4]
[V1505-T-E4]
9Y1210822ENS0077US0
Cylinder Head Surface Flatness
1. Clean the cylinder head surface.
2. Place a straightedge on the cylinder head's four sides and two
diagonal as shown in the figure.
3. Measure the clearance with a thickness gauge.
4. If the measurement exceeds the allowable limit, correct it with a
surface grinder.
• Do not place the straightedge on the combustion chamber.
• Be sure to check the valve recessing after correcting.
9Y1210822ENS0078US0
Top clearance Factory specification
0.80 to 1.0 mm
0.032 to 0.039 in.
Top clearance Factory specification
0.55 to 0.75 mm
0.022 to 0.029 in.
Tightening torque Cylinder head screw
64 to 68 N·m
6.5 to 7.0 kgf·m
47 to 50 lbf·ft
(1) Plastigauge
(2) Crushed Plastigauge
(3) Scale
Cylinder head surface
flatness
Allowable limit
0.05 mm
0.002 in.
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