C3 1969 L71 cast date

[Rich G.]

There is a 69 advertised and the serial # indicates a 12/68 build. The block cast date is "I 14 8" Which I think from the JG is Sept. 14, 1968. The assy stamp indicates a 12/10 date. This info comes only from the ad. Does the spread between the cast date and assembly date seem too much? I know the JG says up to 6 months between the car and the motor, but in reality I thought this would be much shorter. Would anybody be suspicious of this, or am I suffering from Corvette Paranoia?

Rich Giannotti

[Jack H.]

Re: C3 1969 L71 cast date

'Typically' the delay runs 2-8 weeks, depending on part and distance from supplier to St. Louis final line. But this is a statistical abberation (the average) remember the story about the fella who couldn't swim and felt safe crossing the river that he was told 'averaged' 2-feet in depth?

If you thumb through Noland Adams' Vol 1/Vol 2 restoration books (unfortunately Noland didn't write a Vol 2 covering Shark cars), and make tables from his customer survey data where he documents 'original' Corvette component part numbers and dates by VIN, you'll quickly reach this conclusion:

While the average delay may well be 2-8 weeks, the standard deviation associated with the distribution is RIDICULOUSLY LARGE!!! We pretty much know today this was the result of imprecise FIFO/LIFO inventory control, failing components being set aside and reworked/returned to the line in batch lots, 'lost' inventory being 'discovered' and repatriated with assy line flow, and so on.

Personally, when I look at a given Corvette (restored or 'non-restored') and I see ALL of the dated components line up nice and orderly within a 2-4 week date band prior to assy, I guess I personally conclude I'm looking at a 'cooked' car... Doesn't mean it couldn't have been that way, and the benefit of the doubt goes to the owner based on our judging rules, but that's sort of like the odds of all nine planets lining up in a perfectly straight line in the heavens!

So, there's a reason for the general NCRS '6-month' rule and it's based on limited but actual data as well as a handful of documented 'worst case' situations. I would NOT doubt the authenticity of the engine in the car you're looking at without further examination. Remember what Ronald Regan told the Russians; "Trust but verify."

[Joe L.]

Re: C3 1969 L71 cast date

Rich-----

By "assembly date of 12/10" I am assuming that you are talking about the engine stamped assembly date. So, in this case, there is an approximate 3 month period between the block cast date and the engine assembly date.

Prior to 1984, all big block engines were cast, machined, and assembled at Tonawanda, NY; the foundry was co-located with the engine plant. So, in theory, there should have been a VERY short time between engine cast and engine assembly since transportation between foundry and engine plant was a short trip across the lot. For whatever reason, though, big blocks often show a considerable time lapse between engine cast dates (blocks and heads) and engine assembly. In fact, the difference is often far greater than the norm for Flint built small blocks which were cast in Saginaw, MI and transported the 40, or so, miles between Saginaw and Flint. The Tonawanda foundry may have cast big block parts in batches and then machined/assembled them as needed.

Another consideration is this: if someone were going to re-stamp a block's engine date and code, why not make it "better match" the "traditional thinking" of the relationship between the casting and assembly dates? If you're going to re-stamp it, you can have whatever date and code you want.

[Rich G.]

Re: C3 1969 L71 cast date

Thanks, Jack and Joe. Yes, the 12/10 date is the stamp pad, which makes sense with the car serial # (December build). It's just that the casting date seemed early, but what you both say makes sense.

"trust, but verify" reminds me of what a friend had dymo labeled on his steering wheel in the days long before 9/11. It said " Trust in Allah, but tie your camel"

Thanks

Rich Giannotti

[David S.]

Re: C3 1969 L71 cast date

My 1969 L68 has a block (P/N 3955270) cast date of I88, engine build date of 10-29-68 and a vehicle assembly date of 11-4-68. Your dates seem to be in the same family.

Dave
NCRS# 36838