C2: Is this a early, late or repro BB manifold? - NCRS Discussion Boards

C2: Is this a early, late or repro BB manifold?

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  • Dan Pepper

    C2: Is this a early, late or repro BB manifold?

    I queried the board earlier regarding whether or not this C2 BB exhaust manifold would be correct for a Feb 23rd '66 build date engine. Seems Feb 20th in '66 was a Sunday which doesn't necessarily exclude it from being cast in '66 on an OT or early AM shift. Questions arose as to whether it was cast in '76 or '66, or if it could be a repro based on the smooth finish and casting marks. Any additional Observations? Opinions? Just trying to figure out if it is truly correct for use on a '66 BB AIR coupe with the above engine build date.
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  • William C.
    NCRS Past President
    • May 31, 1975
    • 6037

    #2
    Re: C2: Is this a early, late or repro BB manifold

    Likely repop, no "tit" on the flat spot.
    Bill Clupper #618

    Comment

    • Geoff C.
      Expired
      • May 31, 1979
      • 1613

      #3
      Could you be a hair more specific? *NM*

      Comment

      • Dick W.
        Former NCRS Director Region IV
        • June 30, 1985
        • 10483

        #4
        Re: C2: Is this a early, late or repro BB manifold

        Most likely 1976 with the smog tube drilling. Only a few 1966 (California) cars had the emissions system. Plus the notation that Clup made about the smooth casting
        Dick Whittington

        Comment

        • Michael H.
          Expired
          • January 29, 2008
          • 7477

          #5
          Re: C2: Is this a early, late or repro BB manifold

          I agree Dick. I would think if someone was going to reproduced this manifold, they would have done it correctly and gotten the casting number location correct. The "GM" is in an entirely different area than it is on the original manifold on my 66. 20 Feb of 1976 was a Monday, a more likely casting day than Sunday, 20 Feb 1966. (don't laugh at my heat riser, it's been that way for 22 years now)




          Comment

          • Joe L.
            Beyond Control Poster
            • February 1, 1988
            • 43193

            #6
            Re: C2: Is this a early, late or repro BB manifold

            Dan------

            This manifold is neither a reproduction nor an original piece. It's a GM SERVICE manifold cast in either 1976 or, possibly, 1986. Given the degree of corrosion pitting that it has suffered, I'd say that it was probably cast in 1976. How do we know it's a GM SERVICE piece? Well, note the large "D" cast on the manifold. That "D" denotes the GM Danville, IL foundry. Most, if not all, original Corvette big block exhaust manifolds were cast at Tonawanda. Some (but not all) have a lare "T" cast upon them.

            During the period that big blocks for Corvettes were being produced at Tonawanda, Tonawanda also cast the manifolds. Sometime after that period the casting was transferred to Danville, IL. For sure the casting was transferred there after 1984 since during that year the foundry at Tonawanda was closed and ALL casting for Tonawanda-manufactured engines was transferred elsewhere.

            I don't think that any "D" casting mark exhaust manifolds are "correct" for Corvette big blocks. However, FUNCTIONALLY the Danville-cast manifolds are better pieces. That's because the Tonawanda foundry cast only gray iron pieces; the Danville foundry cast only ductile or nodular iron pieces. Ductile or nodular iron is better and stronger than gray iron. That's also the reason that a new-condition Danville piece is smoother than a new-condition Tonawanda piece.
            In Appreciation of John Hinckley

            Comment

            • Dan Pepper

              #7
              Those membership dues were well spent!

              Thanks guys. Again, your input is an education. I have a set on the car cast in '73, but I'll keep looking for real/correct period units.

              Comment

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