Cylinder Bore and Connecting Rod Journal Code Locations

Cylinder Bore Diameter and Connecting Rod Bore Code Locations





Calculate the difference between cylinder bore diameter and piston diameter. If the clearance is near or exceeds the service limit, inspect the piston and cylinder bore for excessive wear.

Rod Bearing Selection
Each rod falls into one of four tolerance ranges (from 0 to 0.024 mm (0.0009 inch), in 0.006 mm (0.0002 inch) increments) depending on the size of its big end bore. It's then stamped with a number or bar (1, 2, 3, or 4/I, II, III, or IIII indicating the range. You may find any combination of 1, 2, 3, or 4/I, II, III, or IIII in any engine.
Normal Bore Size 58.0 mm (2.28 inch)
Inspect the connecting rod for cracks and heat damage.

Connecting Rod Bore Code Locations








Numbers or bars have been stamped on the side of each connecting rod as a code for the size of the big end. Use them, and the letters or bars stamped on the crank (codes for rod journal size), to choose the correct bearings. If the codes are indecipherable because of an accumulation of dirt and dust, do not scrub them with a wire brush or scraper. Clean them only with solvent or detergent.