Engine build date to production # question

[George W.]

Hi all, I have a 321 block that was cast H187, and has a build date of T0901IM with serial # 18S404730. My question is: Since the 4,730th Vette would have beed produced in the later half of Nov. '68, isn't the build date of Sept. 1st way to early? What are considered to be the norms for cast date to build date stamp to vin? Thank you in advance, G.

[Randy R.]

Re: Engine build date to production # question

I'm not an expert, however 6 months is the NCRS cast to build time-frame for judging and point deduction. We recently had a judging school where Al Grenning showed us that he has records that it can take more than 12 months between cast and build!

[George W.]

Re: Engine build date to production # question

Randy, thank you for your responce. I was aware of the 6 month window between cast and build, but my real question is concerning time between build and car production. Actually, I have two questions: 1) Is 14 days between cast date and engine assembly stamp pad date too close? 2) Is 75-80 days between engine stamp pad date, and car build dat, too long? G.

[Randy R.]

Re: Engine build date to production # question

Like I said, I'm no expert but my feeling on question 1 is 14 days could be fine since engines are flying into the plant for assembly into a car but they could sit around since UAW workers of the time probably did not adhere to "first in first out" production methods. Now question 2 seems quite long to have a Corvette sitting around for it's engine. Most likely if the engine had a problem they would pull it from assembly, repair it, grind off the engine stamp and restamp it for another car. That's my $.02.

[Jack H.]

Re: Engine build date to production # question

The general rule is dated parts should preceed the final vehicle assy date by 0-6 months. In certain isolated cases (low production build items like L88 engines, certain glass, Etc.) the six month rule is set aside for these exception items.

That means you can NOT have an engine stamped 6-months before the car's build date made up with dated components that preceed the stamp pad date by an additional 6-months for a 12-month total spread. All must preceed the final assy date of the car by 0-6 months.

Now, on the block cast date vs. block stamp pad date issue, the dated components of the engine must preceed the stamp pad date. But, you can find some real head scratch situations where the block's cast date is the SAME as the stamped engine assy date....

Tonawanda was a single site facility for both castings and engine assy. So, it's not unusual for a block to have been cast on one shift, move across the campus facility and wind up being assembled into a finished engine on the same physical day.

It's a little harder for that to happen on SB engines that were cast in Saginaw and them moved 40-miles down the road to Flint for engine assy, but it DID happen occassionally by random chance.

On longer delays between casting and engine assy, that's simply a matter of inventory control at the engine assembly plant. How long did a given block, head or intake sit in inventory before it was pulled for final assy? It wouldn't be the first time a given casting wound up sitting at the 'back' of the shelf for quite some time before inventory depleted enough for it to 'pop' out and be pulled!

Plus, when a given engine was assembled and happened to fail final test, it might sit for some period of time until techs could disassemble it and repair it. Some might have been 'repaired' by recycling functional sub-assy components (intake, heads, Etc.) onto another fresh block.

Bottom line, there is no 'correct' answer as to how far before this/that event a set of dates should line up. You can read the Noland Adams survey data in his Vol 2 book and track dated components by car/VIN. If you're statistically oriented, take the info Noland gives and run a mean + std deviation calculation. I think you'll be surprised by how large the std deviation/variance is with respect to these dated components!!!

That's why when I judge a car and see ALL of the dated components line up nice and regularly with a 2-4 week time window, I smell a rat... It was a lot more random then we give credit for back then which is why the NCRS 0-6 month rule exists.

[Patrick H.]

Re: Engine build date to production # question

That's why when I judge a car and see ALL of the dated components line up nice and regularly with a 2-4 week time window, I smell a rat... It was a lot more random then we give credit for back then which is why the NCRS 0-6 month rule exists.

Both my 71 and 72 have virtually all their components built within a 2 week time window. My take is that there was a lot more "just in time" assembly than we give them credit for, and it's when I see parts that are slobbered throughout a 6 month time period that I smell a rat.

Patrick

[George W.]

Re: Engine build date to production # question

Okay Jack, what I think you are saying is that: 1) "T" big blocks could have a very close casting date to engine build date, and 2) a stamp date on the block could very well appear in a car produced 2 or more months later. Is this correct? G.