POINTER 3L1650 - Caterpillar

Centering rings given above are for use in oversize main bearing bores. All of these centering rings are for .025" (0.64) oversize main bearing bores, except the 6V138 Centering Ring. The 6V138 Centering Ring is for use in .010" (0.25) oversize main bearing bores. 3 To initially set the micrometer in the bracket assembly, measure the diameter of any centering ring (3) with an outside micrometer that is known to be accurate, and set micrometer (4) to the exact dimension of the ring. Place the ring on the fixture and push the micrometer until spindle (5) lightly touches the ring, then tighten bolt (6). Back off the micrometer thimble and recheck. Repeat the above steps until the micrometer reading is accurate. 4 Place centering rings (3) on each side of the caps that are being replaced.5 To bore an end cap, place centering rings (3) in the second and fourth main bearing bores. 6 Place the unbored new caps (7) on the block with the part number on the same side as the originals. Stamp each new cap to correspond with the number stamped on the pan rail. Tighten the cap nuts as specified in the Service Manual. Place the original bearing caps over centering rings (3), but do not tighten the nuts. 7 Oil boring bar (8) and insert it through the centering rings. Tighten the caps to a torque of 10-20 lb. ft. (14-25) minimum while spinning the bar to check for binding. The centering rings must be seated securely in the bearing saddles after tightening. 8 Bearing assembly (9) and bridge (10) are used when the centering rings do not provide sufficient support for the boring bar; place bearing assembly (9) on the bar, adjust the bearing by tightening bolt (11) until the bar begins to bind, then back off until the bar spins easily. 9 When boring an end cap, place a bridge on the opposite end of the block. When boring center caps on a long block use a bridge on both ends.10 Use bridge extensions (12) with bridge (10) for the 6.25" bore V-engines. 11 To install bridge (10), loosen the bolt and rotate the bridge 45° to slip over pin (13). Position the bridge with the thicker portion down, nearest the boring bar. Loosen bolt (14). 12 Install two dial indicators (A), with magnetic bases (B), in the location shown. [Contact point of one dial indicator to be on the side of bar (8), and the contact point of the other dial indicator to be on the top of bar (8).] 13 With bolts (14), (15) and (16) loose, adjust the dial indicators to zero, while spinning bar (8). Tighten bolts (15) finger tight. Tighten bolt (16) lightly, then tighten bolt (14). Tighten bolts (15), then tighten bolt (16). Loosen, then tighten bolt (16). Spin bar (8) and observe the dial indicators. Both dial indicators must read