NMWR-9-2815-220 Overhaul Manual for M60 M88 Engine AVDS-1790-2CA, AVDS-1790-2DA, AVDS-1790-2DR Download
Page 197 of 1014
NMWR 9-2815-220 CYLINDER ASSEMBLY OVERHAUL—Continued 0012 00 RECLAMATION – Continued 2. Reclamation procedure for installing mismatched rocker covers on cylinders. Cylinders with non-repairable rocker covers may be reclaimed by hand fitting with rocker covers generated from disassembly of salvaged cylinders. Follow the procedures outlined below to hand fit covers to cylinders. (a) Procedure for selecting covers. (1) Remove two dowel pins from rocker cover surface of cylinder. (2) Select a rocker cover that most nearly matches the camshaft bearing bore and cylinder width. (3) Lap mating surfaces of cylinder head and rocker cover with fine lapping compound, to provide a good oil tight contact face. (b) Procedure for fitting rocker cover to cylinder. (1) Use a 1/4-inch drill bit to drill rocker cover dowel holes through from inside to outside of rocker cover. (2) Assemble rocker cover to cylinder and check camshaft bearing bore dimension. Dimension must be 1.4115 –.4125 in. (35.8521 – 3.58775 mm). If camshaft bore is greater than the prescribed dimension, remove cover from cylinder. Machine mating surface of rocker cover to obtain the correct dimension. After obtaining correct camshaft bearing bore dimension, loosely assemble rocker cover to cylinder. (3) Install a plug machined to 1.4080 – 1.4100 in. (35.7632 – 35.8140 mm) diameter by 2.500 in. (63.500 mm) long in the camshaft bearing bore to align rocker cover to machine surface of the cylinder. Align the rocker cover to obtain a 6.2460 to 6.2540 in. (15.8648 – 15.8852 parallel dimension between the rocker cover and cylinder head at the side mounting surfaces, and a dimension of 2.5000 to 2.5015 (63.5000 – 63.5381 mm) inch at the camshaft drive housing bore. Tighten rocker cover mounting capscrews to 100 lb-in (11.30 N•m). (4) Enlarge existing 1/4-inch dowel pin holes using a 19/64 inch drill bit. Drill holes through the rocker cover and 1/2 inch below the contact face of the cylinder head. Ream hole to 0.3090 – 0.3100 in. (7.846 – 7.8740 mm). Remove rocker cover and countersink dowel hole in cylinder head 90 degrees to 0.3400 in. (18.630 mm) diameter. Install 0.3125 x 0.6200 in. (7.9374 x 15.7480 mm) long dowel pins in cylinder head to a height of 0.1900 in. (4.8260 mm) above rocker cover surface. (5) Ream dowel holes in rocker cover 0.3125 – 0.3135 in. (7.9375 – 7.9629 mm) to 0.3000 – 0.3600 in. (7.6200 – 9.1440 mm) depth. Countersink 90 degrees to 0.3400 (18.630 mm) diameter. Install 0.3125 x 0.3800 in. (7.9375 x 9.6520 mm) long dowel pin in outer end of each of the dowel holes in the rocker cover. Drive pin 0.0300 in. (0.7620 mm) below surface. Peen outer end of hole to prevent loss of dowel pins. (6) Install rocker shafts in rocker cover and assemble to cylinder head using proper quantity of mounting capscrews. Torque the four valve rocker bearing capscrews to 275 to 325 lb-in. (31.06 to 36.71 N•m).and the remaining capscrews to 100 lb-in. (11.30 N•m). Line bore camshaft bearing bore to 1.4115 to 1.4125 in. (35.821 0 35.878 mm). diameter. 0012 00-7 Change 1