Special Engine Marks

Information identifying oversize and undersize components are stamped in the following locations:

• O - On side of lifter bore indicates .010" (.25 mm) oversize lifters.
• Letter Code - The original cylinder size is stamped with a code letter on the block near each cylinder on the oil pan rail.
• .010" - Stamped on number 6 counterweight indicates .010" (.25 mm) undersize crankshaft rod journals.
• 3, 5, 10 or 13 - Stamped on inboard side of cylinder head above intake manifold indicates oversize valve guides are used in .003",.005", .010" or .013" (.08, .13, .25 or .33 mm) oversize. Standard valve guides have no stamping.