C3 Stamp Pad "Grind Out"

[Rich G.]

Has there ever been any DOCUMETED evidence that the factory would have ground off the VIN and restamped a motor. I know it is possible, or even probable, but has anyone ever said or written "I worked there and I saw this done."?

I have a 68 L71 that is like this. Some of the guys in the MetroLI Chapter have seen it. The stamp pad in the area of the T0708IR stamp looks good but the VIN has been ground off and restamped. You can feel the impression with your finger. Someone using a scope thought they saw the remnants of other digits.

I am mostly curious about this. I'm not into the points lost or gained by this, but it's another one of those curious things I'd like to know more about. I think I know the whole history of this car. The motor was out before I got it, but the guy who did it swears it is the same one. Unfortunately, he didn't take any pictures of the stamp pad before and after. I realize that even if we know this was done from time to time at the factory, there is no way to prove that's what happened to my car.

Anybody have a car like this that they KNOW was done by GM?

Rich

[Michael W.]

Re: C3 Stamp Pad "Grind Out"

Sure. I know of one car myself, still in the hands of the original owner. Al Grenning has photos of lots of them.

[Warren F.]

Re: C3 Stamp Pad "Grind Out"

Rich:

At the Berkeley regional meet, last month, there was a 1970 coupe that had a factory grind out on the stamp pad. Chuck Berge, the '68 to '72 Team leader was there judging, he actually pointed this out to show me an example.

[David N.]

Re: C3 Stamp Pad "Grind Out"

To all with that unwanted ground off by the machine shop guys,

As a retired FoMoCo laboratory quality control test engineer I know that it is possible to raise those original numbers and letters. It requires access to some acids for making up 2 alcohol based solutions and alternately swabbing the pad with them and allowing the weak acids to slowly preferentially etch the "stressed areas" (those pesky stamps do that to cast iron) and just like magic, they will reappear. I have one of those BB pads, one of these days I will do my own!

David Nims member 19639

[Rich G.]

Re: C3 Stamp Pad "Grind Out"

Thanks Mike, Warren and David.

Are those pictures in Al's book? I've been meaning to buy a copy. I guess there's no time like the present.

BTW, I don't need to raise any numbers, my vin is on there. It's just that it's obvious another number was there first.

Rich Giannotti

[Warren F.]

Re: C3 Stamp Pad "Grind Out"

Rich:

I have not seen Al & Roy's book. This was the first time out for this 1970 coupe for judging.

[John H.]

Re: C3 Stamp Pad "Grind Out"

Al has lots of examples of engine plant grind-outs of the engine plant stamp, but I'm not sure I've seen many of the assembly plant VIN stamp. Anything is possible, but I spent most of my career in assembly plants, and I never saw a grinder on an engine dress line, including the repair station at the end of the line. The Engineering-issued procedure for correcting a bad VIN derivative stamp was to "X"-out every character of the bad stamp and to re-stamp the correct VIN derivative adjacent to it. It'd be pretty hard to go at the pad with a grinder in the assembly plant with all the other dress stuff in the way (fuel line, accessory brackets, etc.).

[Warren F.]

Re: C3 Stamp Pad "Grind Out"

John:

That's what this pad was. It had some kind of grind marks with a line of X's straight across the previous stamping.

[Wayne W.]

Re: C3 Stamp Pad "Grind Out"

I am with John. I think it unlikely that the car assembly line ground and restamped a VIN. That was a pretty sensitive subject even. I think that the proceedure would have left the stamp pretty much intact and then restamped so it could be seen what was done. I am sure that it was done differently by different line workers. But, the one real example that I know of, was restamped with the correct number (one number off) over the old, and then restamped again. It had tree distinct stamps, the old and two new ones. However, if by chance, the engine went back for a major repair, it may have been ground off. Who knows.

[Dick W.]

Re: C3 Stamp Pad "Grind Out"

Wayne, there was a 71 at Bowling Green with a ground out of the VIN. Pretty well matched two more 71's that were in out photo album. Looks like they used a die grinder to do so. I know the official line was to do as John stated, X out the error and restamp. But I have seen more grind outs than I have X's. Ya wonder.......

[mike cobine]

Re: C3 Stamp Pad "Grind Out"

I guess the next step we will see in Barret Jackson is the "rare grind out and restamped original engine".

[mike cobine]

when restoring a Corvette

which car does the engine go into as original? The first one that was ground out or the second one with the restamp?

[Harmon C.]

Re: when restoring a Corvette

You would be real lucky to find a block with the correct factory assembly stamping and only need to change the VIN. For 25 points I would leave it alone and take the hit. Lyle

[Joe L.]

Re: C3 Stamp Pad "Grind Out"

Rich-----

Many years ago I had the privlege of meeting, listening to presentations of, and conversing at length with George Barlos. George worked at St. Louis Corvette for many years. George mentioned on many occasions that incorrect VIN stamps were sometimes corrected by grinding out the mis-stamped number and re-stamping the correct one. If I recall correctly, George said that if there was only 1 or 2 characters mis-stamped (e.g. when the last character or two was not changed from one car to the next), they would ordinarily just "X out" the incorrect characters and stamp the correct ones above or below. However, if there were more incorrect characters, they would grind out the whole thing and re-stamp over it.

[Rich G.]

Re: C3 Stamp Pad "Grind Out"

Joe

Thanks for that information.

Rich