1967 block in 1966 Corvette

[Jim C.]

Hi All,

One of the many things about the Corvette hobby that I really enjoy is the "numbers" (casting numbers, date codes, stamp pads, etc.) I currently own a very late 1966 SB 327/300 with a 1967 cylinder case (block). The common casting number for the 1966 SB is 3858174, however my car has a block casting number that is more common to the 1967 SB Corvette, 3892657. I'm fairly certain the motor is original to my car. What I'm more interested in knowing is how many other original 1966 SB Corvettes are out there with a 1967 block. Helpful information would include the the unit/last digits of the VIN, the engine code on the stamp pad, and the block casting date. The info on my car would look like this: 27592, F0726HE, G116.

I'm interested in how early 1967 blocks started showing up in 1966 cars, what day(s) this occurred on, and possibly drawing other conclusions about what may have been happening on the assembly line during those last days of 1966 production. Any responses will be greatly appreciated.

Jim Cicchini

[Rich G.]

Re: 1967 block in 1966 Corvette

I may be wrong, but I think the 66 TM and Judging Guide covers this issue. I don't have my copy handy, but you should get one if you don't already have it. I'm sure someone else will comment.

Rich G

[Jim C.]

Re: 1967 block in 1966 Corvette

Hi Rich,

You're right. The judging guide does say that a 1967 block can be found in a late production 1966 Corvette. I'm more interested in trying to find what cars that actually happened to in 1966. I'm trying to see if that occurred on a specific date or during a specific week. I'd like to know how many original cars are still out there with this occurrence. I'd also like to know how close such occurrences were in sequence to my car. Basically, why did my car get a 1967 block, when other SB cars coming down the line before and after my car did not? I'm interested in the fact that it happened, and was hoping to possibly draw some conclusions based on any responses that I might receive. I'm not sure that it happened too often, so I might not get any responses and will never really know. I just thought it would be interesting to find out more about it. Thanks for your response.

Jim

[Rich G.]

Re: 1967 block in 1966 Corvette

Hi Jim

Sorry I answered the wrong question.

I always thought it was a cutover at a specific date, but I have no reason to know that, I just assumed it.

Good luck with the search. The results should be interesting.

Rich G

[Terry M.]

Re: 1967 block in 1966 Corvette

In situations where the casting configuration, and thus the casting number, was changed to facilitate the next model year production, it was common to stop the old casting short of the change-over point so that all the "old" parts would be out of the system before the introduction of the new part. Obviously, this only worked if the change in casting configuration allowed the use of both the old and new internal parts. If some of the parts were interdependent then the change had to be more closely orchestrated.

There was a change in cylinder case casting numbers from 1953 to 1954. I am told this change took place during late 1953 production. An example I am more familiar with was the change in Mark IV cylinder case configuration, and thus casting number, during 1969 production to make room in the lower case for the longer arm of the 454 cid crankshaft. Late 1969 corvettes, and other model lines with 512 blocks, will accommodate a 454 crankshaft as a drop-in. In this case it was all preparation for 1970 model year production of 454 cid engines.

All this is about managing parts chnage-over in a production facility -- and I would bet John Hinkley can tell us more than a little bit about that.

[Jim C.]

Re: 1967 block in 1966 Corvette

Good information Terry. Thanks for your interest in my question. That might answer why this happened to my car, but I'd still like to get an idea of how many 1966 Corvettes are still out there like this. Based on the lack of responses, perhaps not many. Thanks again Terry.

[Patrick H.]

Re: 1967 block in 1966 Corvette

Based on the lack of responses, perhaps not many.

Just a guess, but you "may" have gotten more responses if the title was something like "3892657 block usage in late 66 Corvettes." By the title of your thread, my guess was that you were just letting us know your 66 had an incorrect engine.

Only an observation.

Patrick

[John H.]

Re: 1967 block in 1966 Corvette

All this is about managing parts chnage-over in a production facility -- and I would bet John Hinkley can tell us more than a little bit about that.

Bringing some of next year's parts into production prior to the end of the current model year was quite common, to make sure the "system" was clean of the older parts - we called these "pull-aheads". In the same vein (but to a much lesser extent), we also had instances where the "new" parts didn't enter production until after the new model year launch - those were called "lag-alongs".

There's far less of that kind of thing these days due to regulatory requirements like emissions and safety certification, compatibility with multiple on-board computer protocols, etc.

[Jim C.]

Re: 1967 block in 1966 Corvette

You could be right about that Patrick. Thanks for pointing that out. I'll try to come up with better subject lines in the future. Thanks for your response.

[Jim C.]

Re: 1967 block in 1966 Corvette

Thanks for taking the time to respond John. That's actually useful information. I don't know how many 1966 Corvettes that happened to, but I know for sure it happened to mine. I see there were a few more listed in the Noland Adams book (mine being one of them). I also wondered why it didn't happen to consecutive small blocks, but just seemed to occur randomly toward the end of 1966 production. I know there were other small block cars very close to mine in sequence, before and after. that received the standard 1966 block casting number. It would seem that once 1967 blocks were introduced to the assembly line near the end of the production run, they would have been put into every small block car from that point forward. I guess not.

[John H.]

Re: 1967 block in 1966 Corvette

It would seem that once 1967 blocks were introduced to the assembly line near the end of the production run, they would have been put into every small block car from that point forward. I guess not.

It took a while to purge the system at the Saginaw Foundry and at Flint V-8 to get an absolute "clean point" for the last 174 block; inventory control in those days at 5500 blocks per day was pretty primitive compared to today's systems.

[Jim C.]

Re: 1967 block in 1966 Corvette

Once again, good information John. Thanks. I guess it makes some sense. I forget that things were probably much more primitive in 1966, particularly relating to inventory control. The last questions are how many 1966s were made with the 1967 block, and how many are still out there?? I'm not sure we'll ever know the answer to either question. But thanks again for your insight on what may have been going on at the factory in 1966.

Jim C.

[Timothy B.]

Re: 1967 block in 1966 Corvette

Why the different part #'s for the engine blocks? I can't see any difference in any of the 327 blocks.

[Tom H.]

Re: 1967 block in 1966 Corvette

Jim !

You'll probably never know the exact number of units built with the 657 block. The thing you need to remember is that the Corvette community is huge and only a small percentage of us even know what a casting number is ! There are probably many cars like yours out there that have yet to have the unusual variation discovered. Fun, aint it !

[Terry M.]

Re: 1967 block in 1966 Corvette

Why the different part #'s for the engine blocks? I can't see any difference in any of the 327 blocks.

Have you checked Alan Colvin's "Chevrolet by the Numbers"? He has a lot of this kind of information.