Main Bearing Selection
Bearing oil clearance can also be determined by using Plastigage or equivalent. Refer to MEASURING BEARING CLEARANCE USING PLASTIGAGE .
| 1 - Crankshaft Main Bearing Diameter Grade Markings |
| 2 - Connecting Rod Bearing Journal Diameter Grade Markings |
The upper and lower main bearings are "select fit" to achieve proper oil clearances. The lower crankshaft main bearing journal diameter grade markings are stamped into the front crankshaft counterweight of the crankshaft. These marks are read from left to right (clockwise), corresponding with journal number 1, 2, 3, 4, 5, 6 and 7.
The lower main bearing shells are marked with a color code indicating bearing thickness. The bearings are available in five different thickness sizes in order to achieve the desired oil clearance.
Crankshaft lower main bearing journal diameter grade markings correspond to specific journal diameters. The chart below identifies the five crankshaft grade markings and their associated journal diameters.
Crankshaft lower main bearing shells are available in five thickness sizes. The chart below identifies the five sizes.
| Engine Block Grading Class | Crankshaft Bore Diameter mm (in.) | Stamp |
|---|---|---|
| A | 66.0070 - 66.0080 mm (2.5986 - 2.5987 in.) | A |
| B | 66.0060 - 66.0070 mm (2.5986 - 2.5986 in.) | B |
| C | 66.0050 - 66.0060 mm (2.5986 - 2.5986 in.) | C |
| D | 66.0040 - 66.0050 mm (2.5985 - 2.5986 in.) | D |
| E | 66.0030 - 66.0040 mm (2.5985 - 2.5985 in.) | E |
| F | 66.0020 - 66.0030 mm (2.5984 - 2.5985 in.) | F |
| G | 66.0010 - 66.0020 mm (2.5984 - 2.5984 in.) | G |
| H | 66.0000 - 66.0010 mm (2.5984 - 2.5984 in.) | H |
| K | 65.9990 - 66.0000 mm (2.5983 - 2.5984 in.) | K |
| L | 65.9980 - 65.9990 mm (2.5983 - 2.5983 in.) | L |
| M | 65.9970 - 65.9980 mm (2.5982 - 2.5983 in.) | M |
| N | 65.9960 - 65.9970 mm (2.5982 - 2.5982 in.) | N |
| P | 65.9950 - 65.9960 mm (2.5982 - 2.5982 in.) | P |
| R | 65.9940 - 65.9950 mm (2.5981 - 2.5982 in.) | R |
| S | 65.9930 - 65.9940 mm (2.5981 - 2.5981 in.) | S |
| T | 65.9920 - 65.9930 mm (2.5981 - 2.5981 in.) | T |
| 1 - Cylinder Bore Diameter Grade Markings |
| 2 - Upper Main Bearing Journal Diameter Grade Markings |
Engine block upper main bearing journal diameter grade markings are stamped into the exhaust side of the engine block near the oil pump. These marks are read from left to right, corresponding with journal number 1, 2, 3, 4, 5, 6 and 7.
The upper main bearing shells are marked with a color code indicating bearing thickness. The bearings are available in five different thickness sizes in order to achieve the desired oil clearance.
Engine block upper main bearing journal grade markings correspond to specific journal diameters. The chart below identifies the five engine block grade markings and their associated journal diameters.
Crankshaft upper main bearing shells are available in five thickness sizes. The chart below identifies the five sizes.
| Crankshaft Grading Class | Journal Diameter Min mm (in.) | Journal Diameter Max mm (in.) |
|---|---|---|
| A | 59.9920 mm (2.3618 in.) | 59.9930 mm (2.3619 in.) |
| B | 59.9930 mm (2.3619 in.) | 59.9940 mm (2.3619 in.) |
| C | 59.9940 mm (2.3619 in.) | 59.9950 mm (2.3620 in.) |
| D | 59.9950 mm (2.3620 in.) | 59.9960 mm (2.3620 in.) |
| E | 59.9960 mm (2.3620 in.) | 59.9970 mm (2.3620 in.) |
| F | 59.9970 mm (2.3620 in.) | 59.9980 mm (2.3621 in.) |
| G | 59.9980 mm (2.3621 in.) | 59.9990 mm (2.3621 in.) |
| H | 59.9990 mm (2.3621 in.) | 60.0000 mm (2.3621 in.) |
| K | 60.0000 mm (2.3621 in.) | 60.0010 mm (2.3622 in.) |
| L | 60.0010 mm (2.3622 in.) | 60.0020 mm (2.3622 in.) |
| M | 60.0020 mm (2.3622 in.) | 60.0030 mm (2.3623 in.) |
| N | 60.0030 mm (2.3623 in.) | 60.0040 mm (2.3623 in.) |
| P | 60.0040 mm (2.3623 in.) | 60.0050 mm (2.3623 in.) |
| R | 60.0050 mm (2.3623 in.) | 60.0060 mm (2.3624 in.) |
| S | 60.0060 mm (2.3624 in.) | 60.0070 mm (2.3624 in.) |
| T | 60.0070 mm (2.3624 in.) | 60.0080 mm (2.3625 in.) |