In the latest Corvette Restorer magazine, there is an article discussing a 67 big block convertible that is thought to be the “last” 67 big block convertible. From the article, one of the issues appears to be a 427 block dated in February even though the car was built in July. The assumption being that the block was built back in the winter but not “ordered” by a customer until July. This seems logical to me under certain circumstances for rare optioned engines but I wonder how common this was during production of mid years or any GM model production for that matter? I have seen pictures of one of the assembly plants in which there were racks and racks of engines waiting to be installed. How much of production was customer special order and how much was factory stock? If I understand correctly, the assembly date of the motor was stamped the date it was made in Flint or Tonawanda but the vin number wasn’t stamped until the engine was installed on the production line. How common would car number 200 have an engine stamp date that was earlier than car number 100?

OR, are the motor assembly plants so far ahead of vehicle production by the end of the run that cars built later in the production have much earlier engine production stamps? I thought the general rule was that most motors were built about 2-3 weeks prior to vehicle production (even though NCRS allows up to 6 months).

 

Production requirements (from customer orders received at the plant) were forecast to the engine plants 30 days ahead of the time they were needed at St. Louis.

Although the foundry at Tonawanda was on the same site as the engine plant (about 100 yards apart), there are many instances where big-block casting dates precede pad-stamped engine assembly dates by several months, and the one in the article is one of them. Inventory control (as we know it today) didn't exist in the 60's, and raw block castings could sit at the foundry for a long time before ending up 100 yards away at the Tonawanda engine plant. There were similar long time spans between Saginaw block casting dates and Flint V-8 engine assembly dates, but they were far less frequent than some of the spans we see from Tonawanda. Those known production anomalies, although not "typical" of daily production, are why there's a six-month allowance between block casting dates and car final assembly dates in NCRS Flight Judging.

 

To further illustrate John's comments, if you pay close attention to '67 '351 block casting dates, you will notice that certain dates recur frequently, while other time periods seem to lack examples. This would lead me to believe that Tonawanda cast a number of blocks at a time, and then finish machined them as needed for actual plant orders.

For example, I have noted a number of '351 castings in the Oct time frame (mainly cast 10/13 and 10/31), relatively few in Nov, and almost to early Jan, followed by a bunch of Jan 23, 1967 castings. Similar patterns occur in earlier months as well as later months.

My observations on this are by no means a scientific study, although such a study would be interesting to me.