LS6 Block Stamps?

[SS427]

John,
If you have access to the trans, check the VIN ob it and compare the two. As you know, they will be exactly the same. Just a thought.
Rick

[rubbinisracing]

Darren,

The first picture looks ok but there is not enough detail to see broach marks. I suspect the second picture to be a restamp. Someone has attempted to add or enhance broach marks on the pad. They are not untouched. Leeds cars do have 3/16" letters for the Engine code and the vin, with the vin being stamped upside down only at that plant. All other plants had the tonawanda number in 3/16" and the vin in 1/8" in 1970. I believe this started in 1967 with big block along with moving the tonawanda number to the left side near the head plug with the vin on the right.

Best way to tell is look for the following:

1.Check the block casting number... should be 512
2.Check the block casting date...should be within 3 months preceeding the build of the car and the Tonawanda date stamp
Tonawanda date should be within a month precceding the build of the car on build sheet or cowl tag
3. Make sure the block is a 4 bolt...this can be done without removing the pan. 4 bolts have larger holes in the side of the block near the oil filter. There are 3 holes in this area. the center hole of the three is tapped 3/8npt on 2 bolts and tapped 1/2npt on 4 bolts
4.Check the head casting numbers....should be 291
5.Check the head casting dates....they should both be very close in date and follow the 3 month prior to build to build date of car and 3 month prior to Tonawanda date.
6.Pull the heads...broach marks should run from front to back accross the entire top surface of the block. If broach marks are not visible then the block has been decked. It is possible to deck a block and leave the stamp pad untouched. If thats the case then take a metal straight edge and put it on its side accross the top of the block with it running across both the stamp pad and the decked surface. There would be a slight ridge or area where light would appear under the straight edge if this were done. If not the entire surface was decked and pad restamped.

The date codes are a rule of thumb and don't apply to copo engines. I usually perform in the order I outlined as its from easiest to hardest and usually don't have to go all the way. Remember that when you sell the car, someone may go to these extremes to determine if the block is original and you could end up with egg on your face if you didn't do your homework. It's not foolproof, just the best way I know.

[Keith Tedford]

Looking at the backwards numbers and letters, the guys often got the "6" and"9" installed in the stamp upside down as well. Somewhere along the line, everything that could be done wrong was done wrong. About the only thing consistent would be that the numbers and letters would be in a straight line.
At 50-60 an hour the job was/is monotonous. Life on the line becomes such a routine that you tend to run on remote control, doing things automatically. When I go out to the line, you wouldn't believe how it can throw the guys off their routine. They start thinking about what they are doing and get completely off their stride by times. The money is the only thing that keeps them on the job. It is pretty mindless work after a while.

[ssl78]

I know and am certain the Leeds car is not a restamp that is exactly how it came I personally know the history of that car i have documented pictures of that car.

[rubbinisracing]

John,

Then post the pictures and help Darren out. Darren, any doubt just pull the heads.

[DarrenX33]

Howard,

I actually posted this with John. We are one in the same on this issue.

Thanks,,

[rubbinisracing]

Maybe you guys can help me out with your comments on these 2 pics. Again, the thing that looks odd with the 2nd one you posted Darren is not the stamped numbers but the surface area it was stamped into. Its fairly easy to stamp the pad but much harder to replicate the broach marks with the correct "chatter" marks. All of it can be faked to where experienced judges cannot tell.
Give me your comments please as I'm always eager to learn

[mockingbird812]

Here are a couple of shots of my car's motor with heads removed during rebuild to show continuation of broach marks.

[370454s]

My 70 Elco LS-6 Stamping Looks Identical and it is Leeds Built,1353 Units later.
Mike