Connecting Rod Bore Code Locations
- Inspect the connecting rod for cracks and heat damage.
- Each rod has a tolerance range (from 0 to 0.024 mm (0.0009 in.), in 0.006 mm (0.0002 in.) increments) depending on the size of its big end bore.
It's then stamped with a code (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.
If you cannot read the codes 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.
Half of the number or bar is stamped on the bearing cap and the other half is stamped on the rod.
Normal Bore Size: 58.0 mm (2.28 in.)