Just comparing numbers on my 71 coupe, and have a question. My car number has the last numbers: 107776 and on the block, that was supposed to be the right engine, reads 107778. What are the odds that someone replaced the engine later in its life with one that was made two numbers before? The casting number at the back of the block is GM 3970010 which is for 70 to 72 vettes, the other number on the front is V0217CJK. Thanks for the input. :confused:

 

I would guess the stamp on the block just did not penitrate enough on the edge. The 6 is really an 8.

CJK is for a 350 LT1 with auto.

Terry

 

Tom,

There are certainly several scenarios that could have resulted in the VIN derivative on your block being different than the actual VIN for your car.

The first is the possibility that you posted; that the engine was somehow replaced during its life with an engine from another Corvette two VINs earlier than your car. The engine would of course have to be the same one that was installed in your car which I gather, it is. While possible, I feel that this is probably the least likely situation.

The second reason is the one that Terry suggested. The stamping process wasn't all that scientific and was done by a human rather than a machine. If the gang stamp was held at an angle or moved as it was struck, it is possible that the top of the "6" was deformed and appears like a "8". You will have to judge if this is the case.

A third explanation is that the VIN derivative was incorrectly stamped at St. Louis. While not common, this did happen and would certainly account for the difference between the two. Here's something to check; the VIN derivative for the transmission was stamped at the same time that the engine was done... If the engine was misstamped, I would expect the transmission to be misstamped as well.

I'd be curious to hear what you discover Tom.

Terry,

While the CJK suffix is often listed as LT-1/automatic, it was actually a base engine/automatic application. Allan discussed this in detail in one of his posts a few weeks ago which you could locate in the archives. The only early LT-1 engines that were available with an automatic were those installed in 1970-72 Z-28 Camaros and 1970 COPO 9010 Novas.

There was a CTR code LT-1 designated for the 1970 Corvettes, but was never actually used. I have always been curious if this was intended to be the code for the LT-1/M-40 combination. Perhaps that information will be discovered someday...

Regards,

 

Hmmm, so the VIN has a 6, but the block has an 8?

It doesn't seem likely that a 6 stamp would end up looking like an 8.

You may want to check the frame for you VIN.

An engine swap doesn't seem too likely.

Sounds like an interesting assembly line story to me :yesnod:


[Modified by jerryp58, 3:51 PM 1/13/2002]

 

LT-1,

I would doubt very seriously that someone changed engines with a car two behind yours. The odds on that are probably millions to one. I would dare say the broach marks did not penetrate the block enough, which I have seen on many ocassions. If you are in a position to look at it with a magnifying glass, ie the engine is out of the car, you can probably see where the stamp is there, but just isn't visible to the eye.

 

I read "that Tom has an engine with the 6 and a vin with the 8" that is why I figured a bad stamp.

Terry

 

CJK is a base 350/270hp for 1971 auto. NOT an LT1.. The chilton/s manual is wrong as well as some early GM data. LT1's have mechanical (solid) valve lifters and were not available with automatics. My guess on the number is that the person who stamped the block when the car was built simply forgot to change the number for some reason... Monday hangover or??? :lol:

 

I just got back from my garage and re-checked the motor, which is out of the car on my engine stand. I checked the block and the number is definately stamped 107776. On the back of the motor on the passenger side it is stamped A 7 6 and on the driver side it is 3970010. The heads have the number 3973487. Where on the frame is the stamp? Thanks for all the help!!!

 

Hey Tom!

Is that A 7 6 CAST into the block, rather than stamped, and located to the passenger side of the distibutor hole. If not, look for another cast code in that location.
If so, are you sure it's A 7 and not A 1 ?

 

Here’s what I found.

Head # 3973487 – Used on all 350 motors from 71 through early 72.
Block # 3970010 – 350 cid motor used from 69 to 79.
Partial VIN # 107776 – Correct for 71.
Partial VIN # 107778 – Correct for 71.
Block date code # A 7 6 – Denotes a January 6, 1976 casting.
Block code V0217CLK – V denotes the plant (not sure which one), 0217 denotes the date of assembly (February 17), CLK denotes a 350/270 HP auto.

These numbers don’t jive. Check the block date code again.


[Modified by 63Banshee, 3:48 PM 1/13/2002]

 

After seeing the casting date, I went back and looked at the original post.

VIN 7778 was built sometime in late January...

Your engine assembly date is in mid February...

Something is not correct here.

Regards,

 

Here’s what I found.
Head # 3973487 – Used on all 350 motors from 71 through early 72.
Block # 3970010 – 350 cid motor used from 69 to 79.
Partial VIN # 107776 – Correct for 71.
Partial VIN # 107778 – Correct for 71.
Block date code # A 7 6 – Denotes a January 6, 1976 casting.
Block code V0217CLK – V denotes the plant (Flint), 0217 denotes the date of assembly (February 17), CLK denotes a 1971 350/270 HP auto.

These numbers don’t jive. Check the block date code again.

Sorry about the dual post... I'm not sure how that happened.


[Modified by 63Banshee, 4:17 PM 1/13/2002]

 

Still seems VERY coincidental that the build numbers are only off by a couple digits. Plus the CJK code - I don't think that was used in '76. I'm still hoping that Tom read the date code wrong. But could it be possible that someone restamped the pad in an attempt to fool a buyer? Then screwed it up by using a 6 instead of an 8.

 

Is this supposed to be an LT-1 motor? If so it should have an aluminum intake. Also, where there any automatic LT-1’s built?

 

Larry, I checked the date code on the passenger side again, and it is an A then it looks like a 7 but it could be a 1 then a 6. The car was originally a base motor 270hp automatic, thus the CJK on the block. Kind of strange about the number on the front, it looks very clean and not re-done.

 

Tom,

What is the FULL VIN derivative on the stamp pad? That may answer some questions.

Even if the "7" is a "1," the last digit determines the year so we're still looking at a 1976 casting date (unless there is a number after the "6").

It still does not address the fact that the engine assembly date is AFTER the vehicle assembly date.

My guess is that your engine is out of a 1976 Chevrolet vehicle that used the same CJK broadcast code as your '71. Either that or a poorly researched attempt at a restamp.

Regards,


[Modified by Rowdy Rat, 5:00 PM 1/13/2002]

 

CJK represented two dii motors in two diff years:

1970: 402cid 325hp, 4bb carb, TH trans in a Chevelle or El Camino.

OR

1971: 350cid 270hp, 4bb carb, TH400 in a Vette..

 

The stamped pad on the pass side is for sure A then 7 and the last number is a 6 for sure. The 7 could be a 1 but not likely. The other stamp is as big as life on the driver side, it is GM3970010. Did that casting number go into the 76 year?

 

Hey Tom!

That casting # ran through '79. When we talked earlier I thought the middle digit represented the year. that's why I thought it it was a 1. I was wrong and it's the last digit like the others have stated. If you've confirmed the last digit as a 6 then it has to be a '76 block. Sorry for leading you astray - I was nearly 100% sure that it was a factory error!

 

As stated...

Head # 3973487 – Used on all 350 motors from 71 through early 72.
Block # 3970010 – 350 cid motor used from 69 to 79.
Partial VIN # 107776 – Correct for 71.
Partial VIN # 107778 – Correct for 71.
Block date code # A 7 6 – Denotes a January 6, 1976 casting.
Block code V0217CLK – V denotes the plant (Flint), 0217 denotes the date of assembly (February 17), CLK denotes a 1971 350/270 HP auto.