HEXA

ENGINE 59 NOTE  Lower and Upper bearings are not interchangeable. 20. Install connecting rod bearing cap with bearing shell on connecting rod. Tighten connecting rod bearing cap mtg. nuts to specified torque. 21. Measure connecting rod bearing bore. Record the readings in the format given in this manual. 22. If connecting rod big end parent bore dimension is maintained within specified limits, proper bearing bore dimension is automatically achieved. 23. However, it must be physically measured and confirmed. Measure pretension of connecting rod bearing shell with a feeler gauge after loosening connecting rod bearing cap mounting nut on opposite side of bearing shell lug. Pretension Gap: 0.120 to 0.180 mm. NOTE  Connecting rod bearing shells are precision finished and should not be bored or scraped. Maintenance Limit Max. permissible taper and ovality of connecting rod big end parent bore cylindricity. 0.008 mm 0.01 mm Max. permissible circularity and ovality of connecting rod small end parent bore. 0.005 mm 0.008 mm Connecting rod small end bush inside diameter (to be finished after installation) (Piston pin oiled has thumb push fit in small end bush.) Ø31.020 – Ø31.033 mm Maximum permissible out of parallelism (bend) between connecting rod small end and big end parent bores, measured at a distance of 100 mm from centre line of connecting rod. 0.06 mm Center to center distance between connecting rod small end and big end parent bores 149 +0.03 mm Maximum permissible twist of connecting rod 0.1 mm Connecting rod big end parent bore diameter Ø53.69+0.019 mm Bearing shell to be selected such that clearance is maintained as 0.011 - 0.065 mm Pre-tension of connecting rod big end bearing shells. 0.060 - 0.090 mm Maximum permissible difference in weight of connecting rods in one engine ±3 gms Connecting rod big end axial play 0.1 – 0.35 mm Stage Connecting Rod small end and big end parent bore dia.(mm) Crank pin journal dia with bearing shell (mm) Normal 50.008, 50.047 50 -0.005,-0.02 Normal 1 49.958, 49.997 49.90 -0.005, 0.02 Repair 1 49.758, 49.797 49.75 -0.005, -0.02 Repair 2 49.508, 49.547 49.5 -0.005, -0.02