Question about LS3 block casting date

Discussion in 'VIN, Trim Tag & Drivetrain Decoding' started by John Hansen, Sep 25, 2020.

  1. John Hansen

    John Hansen New Member

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    Sep 25, 2020
    Hello all-

    Looking at a '71 SS/RS, with the 396. VN car with build sheet. Have found the VIN stamp on the block by oil filter. My question is what I view as a pretty questionable discrepancy between the block casting date of Jan 28, 1970 (A2870) and the assembly stamping of 08/18. Car was built 3rd week of September, 70. Just a hair over 6 months from block casting to engine assembly. That seems like a long time for a casting to just be sitting around... I know there weren't many LS3's built, anyone have educated thoughts on this spread in time? I'm comfortable with the condition of the upper stamp pad, it looks good. I'm not quite as well versed with the lower VIN stampings. Thanks in advance!
  2. DessertRat

    DessertRat Member

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    Sep 3, 2018
    Hi John,

    I’m sure some owners here with numbers-matching cars can weigh in for a comparison.

    I have a question for you. What do you mean when you say that you are comfortable with the condition of the upper stamp pad?

    I’ve heard of people stamping their own numbers on blocks to make them look like they are original to the car. Is that what you mean?

    I’m not trying to hijack your thread. I was just wondering at what point in time did people begin stamping their own numbers on blocks to pass off as being numbers-matching to add value?

    I have a 71 RS/SS Van Nuys car also, but it doesn’t have the original engine or trans so I can’t give you a helpful comparison.

    Fortunately I have a partial build sheet that shows it’s an LS3 4 speed car.

    Nice find on that car!

  3. badazz81z28

    badazz81z28 Veteran Member

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    May 4, 2001
    I know this is an old post, but I don't think there is much to be concerned about unless the casting date is after the cars build date or the casting is unrealistically super close to the build date. You have to consider blocks were casted in mass and who knows how long it could have been sitting up to the point where the engine was actually built and when it was actually installed in a car. If the build sheet verifies the car is a LS3 and the cars VIN is on the block where its supposed to be, I think you can bet its original. Like you said, they didn't build a ton of them in comparison so its reasonable to have a BBC engine waiting for a car.

    Do you have a pic?
  4. Kricka

    Kricka Veteran Member Lifetime Gold Member

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    Sep 26, 2002
    Skellefte. SWEDEN
    My car has a similar timeframe.
    Engine cast date 23/6-71 (F23 71). Assembly date 7/12-71 (1207). Car was built second week of december (12B).

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