1970 Corvette Big Block Engine Pad

[Richard J.]

Hello all... I am wanting to verify an engine stamping as being correct for a 1970 but am unfamiliar with 1970 VIN stampings on the big block engine stamping pad. I have been told I should see several different things and all I can say for sure is 1970, and some 71's may be alike, the rest of 1971 is different and 1972 different again??? Can I please git some confirmation from a 70 to 72 Shark expert or two? If anyone has a picture or two they would care to share that would be great too!! Thanks Rick

[Kenneth B.]

Re: 1970 Corvette Big Block Engine Pad

Hello all... I am wanting to verify an engine stamping as being correct for a 1970 but am unfamiliar with 1970 VIN stampings on the big block engine stamping pad. I have been told I should see several different things and all I can say for sure is 1970, and some 71's may be alike, the rest of 1971 is different and 1972 different again??? Can I please git some confirmation from a 70 to 72 Shark expert or two? If anyone has a picture or two they would care to share that would be great too!! Thanks Rick

OK
Post a picture or at least let us know what #'S are on the pad now. I doubt any one else has a picture of your pad.
KEN

[Richard J.]

Re: 1970 Corvette Big Block Engine Pad

Hello again... The car has a P.O.P. and that number matches the Tonawanda Stamp. I do not have a picture that is clear but the number are as follows... T0I08CZU and in very small type is either a 70S4059XX or 10S4059XX, the picture is unclear. My question is what format is correct or are they both wrong? I want to know what it should be before I have this person verify what is stamped there and I ask for a better picture. Thanks, Rick

[Joe L.]

Re: 1970 Corvette Big Block Engine Pad

Hello again... The car has a P.O.P. and that number matches the Tonawanda Stamp. I do not have a picture that is clear but the number are as follows... T0I08CZU and in very small type is either a 70S4059XX or 10S4059XX, the picture is unclear. My question is what format is correct or are they both wrong? I want to know what it should be before I have this person verify what is stamped there and I ask for a better picture. Thanks, Rick

Rick-----


The stampings sound ok to me. The VIN derivative stamping which is the smaller font size series and stamped at St. Louis should begin with "7". The last 5 digits should match the last 5 digits of the car's VIN number.

The larger font size stamping is the engine assembly code. The "T0I08" indicates it was assembled at Tonawanda, NY on January 8. The year has to be determined by referring to the engine casting date. In your case, the last digit of the casting date should be "0", indicating 1970. The suffix code of "CZU" is correct for a 1970 LS-5 with 4 speed transmission.

[Tom L.]

Re: 1970 Corvette Big Block Engine Pad

Wouldn't you expect to see a very late 69 casting date with a January 8, 1970 build date?

[Tom L.]

Re: 1970 Corvette Big Block Engine Pad

I have an additional question. Based on the VIN, the car should have a body build date of March 9th or 10th. I understand the NCRS six month rule, however, I've also heard that the typical gap between the engine build date and the body build date was between one to six weeks in big blocks of this era. I don't mean to suggest that there is an issue with the car Rick is looking at, rather, I' trying to get an understanding of how much of a gap should raise suspicion. Thanks.

[Joe L.]

Re: 1970 Corvette Big Block Engine Pad

Wouldn't you expect to see a very late 69 casting date with a January 8, 1970 build date?

Tom-----


There is often a very short time between engine cast date and engine machine/assembly date. In fact, it's even more likely for Tonawanda engines since the foundry was right next door to the engine plant. However, some big block castings do show a fairly long time between casting and machining/assembly. Certainly, this was not the general rule. It's very possible, though, that the block was cast in late 1969. I should have mentioned that in my previous post rather than saying that the block cast date should end with a "0".

[Joe L.]

Re: 1970 Corvette Big Block Engine Pad

I have an additional question. Based on the VIN, the car should have a body build date of March 9th or 10th. I understand the NCRS six month rule, however, I've also heard that the typical gap between the engine build date and the body build date was between one to six weeks in big blocks of this era. I don't mean to suggest that there is an issue with the car Rick is looking at, rather, I' trying to get an understanding of how much of a gap should raise suspicion. Thanks.

Tom-----


At St. Louis the engines were not necessarily dispatched to the assembly line on the basis of first in, first out. Very often, it was last in, first out. So, an engine could remain in the engine bay for quite awhile if it was towards the rear of the bay. That's one of the reasons that I believe NCRS uses the "6 month rule".

[Richard J.]

Re: 1970 Corvette Big Block Engine Pad

1970 is a very funny year for big blocks, I already know this... It is not uncommon to see a September/October Casting Date with a January build in an Early March car. My question is about the VIN derivative that is stamped on the engine pad. 70 is unique and I want information on EXACTLY what the format is before I look any further into this issue with the fellow I am talking with. Should I see a 70S4XXXXX or 10S4XXXXX? I think it is the 70S4XXXX. I know engine assembly dates.... I know what is acceptable for spans between casting dates, assembly dates and when they were installed in the cars. 1970, especially early in 1970, was a real learning curve for St. Louis as the 454 was new, production stated 4 months late and there was a big strike that had just come to an end... I know this all, I would like some proof of how the VIN derivative should be stamped into the block on the engine pad. Thanks

[Tom L.]

Re: 1970 Corvette Big Block Engine Pad

My June of 1970 LS-5 VIN stamp is 70S412XXX. It is identical to the VIN stamp on the transmission. The same stamping tool was used on the block and transmission.

[Joe L.]

Re: 1970 Corvette Big Block Engine Pad

1970 is a very funny year for big blocks, I already know this... It is not uncommon to see a September/October Casting Date with a January build in an Early March car. My question is about the VIN derivative that is stamped on the engine pad. 70 is unique and I want information on EXACTLY what the format is before I look any further into this issue with the fellow I am talking with. Should I see a 70S4XXXXX or 10S4XXXXX? I think it is the 70S4XXXX. I know engine assembly dates.... I know what is acceptable for spans between casting dates, assembly dates and when they were installed in the cars. 1970, especially early in 1970, was a real learning curve for St. Louis as the 454 was new, production stated 4 months late and there was a big strike that had just come to an end... I know this all, I would like some proof of how the VIN derivative should be stamped into the block on the engine pad. Thanks

Rick-----


That kind of "proof", I don't think that anyone is going to be able to give you here. For one thing, these stampings were never done in a precise sort of manner. Your best bet if you want to verify the stamping is original is to consult with Al Grenning. Al has done a long-term, major study of block stampings. I'd say he's the one that's in the best position to render an opinion on the authenticity of the stamping in question.

[D S.]

Re: 1970 Corvette Big Block Engine Pad

First, I wold like to encourage you to register your '70 with the 1970 Corvette Registry. It has a photographic library and there are three or four clear photos of what the engine pad shows as far as stamping.

http://corvetteforum.net/c3/1970registry/1970registry.html

http://corvetteforum.net/c3/1970registry/mechdetails.html

[Warren F.]

Re: 1970 Corvette Big Block Engine Pad

Rick,

Good to hear, that you frequent this board, now and then.

I had 3 '70 LS5 Corvettes, vin#'s 6664, 7272, & 8373. All had the vin sequencing as 70S406664, 70S407272, & 70S408373 as stamped on the engine pad area.