Engine date vs Build date

[William]

True.

Not unusual for 512 blocks cast in January [A49] to be used for COPO L72 engines assembled in April.

Z/28s were a different story. Early in the MY, not unusual to see engines final-assembled the day after the block was cast. Also, have two later examples cast & assembled the same day.

Heard a story about '67 Corvettes with the standard 300/327 engine. Chevy needed to convert the intake manifold tooling. They ran off all the castings needed for the '67 MY Fall '66 and shut it down. No matter when the engine ended up getting built, it will have an intake manifold cast August or September '66.