NANO

130 ENGINE 273 MPFI • Big-end thrust clearance: Check the big end of each connecting rod for thrust clearance, with the rod fitted and connected to its crank pin in the normal manner. If the clearance measured is found to exceed the limit, the connecting rod or the crankshaft, whichever is responsible for the exces- sive clearance, must be replaced. SR. ITEM STD VALUE LIMIT a Axial Play 0.05 to 0.35 mm 0.4 • Connecting rod alignment : Mount the connecting rod on the aligner to check it for bow and twist and, if the limit is exceeded, replace it. Ensure that connecting rod big end and small end axes are parallel to each other and are within speci- fied limits. Ensure that centre distance between small end to big end is maintained within specified limit. Install connecting rod bearing caps without bearing shells on connecting rod. Tighten connecting rod bearing cap mounting nuts to specified torque. Ensure that identification numbers for connecting rod and connecting rod bearing cap are matched and notches for bearing shells are on the same side. Check twist and bend of connecting rod by using new piston pin in connecting rod small end. Measure twists and bends of connecting rod with feeler gauge with respect to vertical face of connecting rod alignment gauge in vertical and horizontal plane at a distance of 50 mm from line joining centers of connecting rod small end and big end bosses. If necessary, straighten connecting rod in cold condi- tion. Since a slight clearance exists between connect- ing rod bolts and corresponding connecting rod bear- ing cap holes, it is possible that connecting rod bear- ing cap once removed may be installed off center, by which dimension of connecting rod big end parent bore will be different in different directions. If there is a dif- ference noticed in connecting rod big end parent bore dimension, connecting rod bearing cap can be centralized by lightly tapping it with mallet in required direction after slightly loosening connect- ing rod bearing cap mounting nuts. SR. ITEM STD VALUE LIMIT a Limit on Bow (at 50mm) 0.03 mm 0.05 b Limit on twist (at 50mm) 0.05 mm 0.1 Connecting Rod Small End : Inspect the small end of each connecting rod for wear and evidence of crack or any other damage, paying particular attention to the condition of its bush. Check the piston pin clearance in the small end. Replace the connecting rod if its small end is badly worn or damaged or if the clearance exceeds the limit.