Note: The number on the tab groove side of the connecting rod is positioned toward the opposite side of the engine from the camshaft during installation.
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| Illustration 1 | g00287964 |
The 1U-6431 Piston Ring Groove Gauge is necessary for measuring ring grooves in keystone style pistons. Refer to the instruction card that is included within the gauge group for the correct use of the gauge group.
Top Piston Ring and Intermediate Ring
(1) Top piston ring
The ring should be installed with the side marked "UP-1" toward the top of the piston.
(2) Intermediate ring
The ring should be installed with the side marked "UP-2" toward the top of the piston.
When the piston ring is installed in a cylinder liner that has a bore size of 120.70 mm (4.752 inch), the specific clearance between the ends of the piston ring is the following value:
- Top ring ... 0.622 ± 0.190 mm (.0245 ± .0075 inch)
- Intermediate ring ... 0.622 ± 0.190 mm (.0245 ± .0075 inch)
For each 0.03 mm (.001 inch) increase in the cylinder liner bore size, the clearance between the ends of the piston ring increases by 0.08 mm (.003 inch).
Oil Control Ring
(3) Oil control ring
The spring ends of the oil control ring should be assembled 180 degrees from the ring end gap. The blue colored portion of the spring must be visible at the ring end gap.
- Width of the piston groove for the new oil control ring ... 3.188 ± 0.013 mm (.1255 ± .0005 inch)
- Thickness of the new oil control ring ... 3.137 ± 0.013 mm (.1235 ± .0005 inch)
- Clearance between the groove and the new oil control ring ... 0.051 ± 0.026 mm (.0020 ± .0010 inch)
- Maximum permissible clearance between the groove and the oil control ring after use ... 0.15 mm (.006 inch)
- Thickness of the new oil control ring ... 3.137 ± 0.013 mm (.1235 ± .0005 inch)
When the piston ring is installed in a cylinder liner that has a bore size of 120.650 mm (4.7500 inch), the specific clearance between the ends of the piston ring is the following value:
- Oil control ring ... 0.572 ± 0.191 mm (.0225 ± .0075 inch)
For each 0.03 mm (.001 inch) increase in the cylinder liner bore size, the clearance between the ends of the piston ring increases by 0.08 mm (.003 inch).
Piston Pin Bore
(4) Piston pin bore (elliptical pin bore)
Bore in piston for pin
- Minor diameter ... 43.188 ± 0.004 mm (1.7003 ± .0002 inch)
- Major diameter (minor diameter plus the following value) ... 0.040 ± 0.007 mm (.0016 ± .0003 inch)
- Clearance between the pin and the bore in the piston ... 0.004 to 0.022 mm (.0002 to .0026 inch)
- Maximum permissible clearance between the pin and the bore in the piston after use ... 0.05 mm (.002 inch)
- Diameter of the new piston pin ... 43.175 ± 0.005 mm (1.6998 ± .0002 inch)
- Major diameter (minor diameter plus the following value) ... 0.040 ± 0.007 mm (.0016 ± .0003 inch)
Note: When the piston is installed in the engine, the "V" mark on top of the piston must be in alignment with the "V" mark on the cylinder block.