Special Engine Marks

Some engines are produced at factory with oversize or undersize components. These engines are identified by a letter code stamped on a boss between ignition coil and distributor. Letters are decoded as follows:

• "B" indicates all cylinder bores are .010" (.25 mm) oversize.
• "C" indicates all camshaft bearing bores are .010" (.25 mm) oversize.
• "M" indicates all main bearing journals are .010" (.25 mm) undersize.
• "PA" indicates one or more connecting rod journals are .010" (.25 mm) undersize.
• "PM" indicates all main journals and one or more rod journal are .010" (.25 mm) undersize.