Thought I had an original engine block, but...

[Ed McGettigan]

...now I'm not so sure. I'll apologize for the length of this message up front. I purchased a 1964 Corvette Roadster in October 1998. It was advertised as a numbers matching car. The car did not come with any useful documentation from previous owners, however, most components appeared original which still appears to be true. My novice review of the engine codes and stampings also led me to believe the block to be original, until last night. I was documenting and deciphering various date codes when I discovered something disturbing after reading the 1963-1964 Corvette Technical Information Manual & Judging Guide. According to The Guide, "The casting date must chronologically precede the engine stamp pad assembly date. Both the casting date and the engine stamp pad assembly date must chronologically precede the approximate vehichle assembly date, but not by more than six months". (pg 77) The engine block casting date on my car appears to be after the assembly stamping date (and the engine block casting date is in the same month as the body build date on the trim tag). Here are some of the pertinent numbers:

VIN - 40867S121531

Build Date from Trim Tag - K10 (I decode as July 10)

Engine Casting Number - 3782870 (correct casting number for 64 Corvette)

Engine Casting Date - G64 (I decode as July 6, 1964 / I have double-checked the "G" a dozen times to make sure it is not a "C", it appears clearly as a "G" to me)

Engine Pad Assembly Stamping - F0429RD (I decode as Flint Plant, April 29, L75 327/300 1x4BC Manual Transmission)

Engine Pad VIN Derivative - 4121531

Is it possible that this is the original block? Or is it more likely an original Corvette block with a restamped engine pad? Am I interpreting something incorrectly? Am I missing something? Needless to say, I am a little bummed right now. How can I be sure what I have. Help!

[kenrobb]

Re: Thought I had an original engine block, but...

In checking in Noland Adams Corvette Restoration & Tech Guide - Vol 2 there are two vettes listed before and after yours. 40867S121385, engine ID 4121385, engine no; F0630SC, block casting date N/A 40837S122152, engine ID 4122152, engine NO. F0709RR, block casting date N/A The vettes before these in the list had engine casting date of F124 on S/N 20778 and F164 on S/N 20721. On page 251 of book. So not sure this helps much, but the date and S/N are in line with others. The block is usually cast jsut several days before the assembly date of teh engine, and then they are shipped to plant in St.Louis. Then engine ends up in a car several days later for car assembly date. Noland's book has a good discription on engine numbers on page 42. too long to go into detail here. Ken

[Joe L.]

Re: Thought I had an original engine block, but...

Ed-----

It is very difficult to say for sure what happened here. One thing that we know for sure, though, is that it is not possible to have an engine machined and assembled before it was cast. Lots of thing are possible, if even remotely so, but this type of occurrence is NOT possible.

Also, I believe that you are correct in your assessment that the "G" is, in fact a "G" and not a "C". That's because if it were a "C" that would mean that the block was cast on March 6, 1964 but not machined and assembled until April 29, 1964. That type of time lag between casting and assembly is POSSIBLE, but quite uncommon.

Also, your engine build date of April 29 is also generally consistent with your car's build date of July, 10. It's a little longer than usual, but well within the range of reality. Keep in mind that folks at the St. Louis assembly plant weren't in the grocery business; they didn't rotate their stock, including stocks in the engine storage area(That's a paraphrase from the late Phil Hawkins, a lontime employee at the St. Louis plant). However, a block casting date of July 6 for a Corvette built on July 10 is another virtual impossibilty, but not a TOTAL impossibility. That's because a car built on July 10 could have, for one reason or another, sat off-line for some reason and received an engine much later than it normally would have been expected to. But, I don't think that's what happened here.

Having said all this, I believe that there is a good chance that your engine is original to the car despite the apparent inconsisteny in the block casting date. Don't forget, folks at foundries, including the Saginaw, MI foundry where your block was cast, are capable of making mistakes. It is very possible that someone used a "G" when they set up the mold that day instead of a "D" which they intended to use. Then, the whole day's production would have been mis-identified as to date. Now, someone may or may not have later caught this mistake, but, without a doubt, GM wouldn't scrap a day's worth of castings because someone had made an error on the date. They just weren't concerned about the effect that this would have on the poor soul that someday wanted to enter the car in NCRS Flight Judging or Bloomington Gold.

There are several reasons for my opinion on this. First, if someone were to go to all of the trouble to re-stamp a block, I would think that they would also go to the trouble of obtaining a block with a plausible casting date. Any block produced in a 2-4 month period prior to assembly would do and these blocks are not that difficult to locate. They were used in a lot of Chevrolets.

Second, if someone were going to restamp a 1964 Corvette engine, why give it an "RD" code? You could just as easily give it an "RT" code or, even, an "RX" code and instantly increase the value of the car by adding a few other rather easily, if not expensively, obtained components.

[Jack H.]

PS

Don't forget in these analysis exercises to take into consideration the source of the car's body to which the trim tag is affixed....

AO Smith cars, built in Ionia, Michigan, had to travel to the St. Louis final assy line just as other functional sub-assy items (like engine). Often, they sat outside awaiting schedule onto the final line. It's MORE than possible for an AO Smith body to exibit a build date that preceeds the engine cast/assy and you have to be careful in dotting the 'i' and crossing the 't' in correct/original assessment in this area.....

[Wayne M.]

Re: PS (A vs. S bodied '64's)

Valid point, Jack, except for 1964 only, as Ionia production of Corvette bodies started around VIN 9xxx, January was A, etc... Ed's K10 trim date automatically pegs his as an S-body.

But I agree with Ed that something seems amiss. Maybe it's the wrong month cast code selected that day, as Joe has said, and if that's the case, maybe someone with an extensive engine #'s data base would be able to document others with the same oddity. Still, in spite of "last in /first out" inventory flow, 2+ months between engine assembly and vehicle completion is a bit of a stretch, especially as the RD blocks were the most popular (by far) engine, and hence the quickest turnover.

Ed should have someone (NCRS judge) check the engine pad, broach marks, etc.

[Loren L.]

Re: Thought I had an original engine block, but...

Get in touch with Al Grenning on this board to see if anyone else in your serial range has ever reported a casting date with a "4" INSTEAD of a "7". The men who loaded these were human. Second thought is to check the dates on the heads - see if they agree with a July casting and if they do, start to relax, because you may be looking at an "anomaly" and it will NOT be the first.

[Edward M.]

Re: Thought I had an original engine block, but...

One thought on this issue that has not come up yet. Forget about the numbers on the front pad for a moment and check the condition of the pad itself. Re-stamping the numbers is easy, getting the correct surface conditions on the pad is tough.

Does the front pad have broach marks on it? Is the front edge of the pad sharp or somewhat dull. Does the front pad have any circular swirl patterns machined into it.

Circular swirl pattern COULD indicate that the block was decked at a machine shop, possibly to remove the old numbers. A sharp front edge would normally go with this. Clear broach marks (and perhaps a somewhat dull edge) would be more consistant with a "typical factory" machining of the block. Of course, if the engine was restamped, and the restamper started with a virgin front pad, then all bets are off.

[Everett Ogilvie]

Casting Date and Assembly Lag

Joe, your response has raised a question. You say that a lag of one month might be too long? Is that accurate for the popular small blocks, but maybe not for later big blocks? I ask because my '66 big block engine was assembled in May '66, and the casting date is February, I THINK (memory disclaimer here - I wil double check the casting date this evening). So that is a 3 month lag if my memory is correct. Maybe the limited production of big blocks caused the blocks to sit around longer and typically have a longer lag between casting date and assembly date? (The car is Bowtie, so "we" feel the dates and pad are not in doubt). I am asking the members here for some inputs on lag time of big vs small blocks to help put things in perspective.

[Tom B.]

Re: Casting Date and Assembly Lag

Everett,

I think both big block casting dates I have (67 and 68) are 2 or 3 months ahead of the other dates. I'll check them both again tonight. TBarr #24014

[Wayne W.]

Re: Casting Date and Assembly Lag

I wouldnt say that BB engines were limited production. It seems that BBs were comparable in numbers to SBs. My 67 was casted on C77 assembled on 0317 and installed in a May 01 S body. Nolands book will give you a good indication in the survey section. You will see that BB production was evidently done on certain days. ie. a lot of C77s or A67s etc. Those production dates are then scattered out over a month or more.