Mr. Joe Lucia, Could You Help Me Verify Some Part Numbers? - NCRS Discussion Boards

Mr. Joe Lucia, Could You Help Me Verify Some Part Numbers?

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  • Russ T.
    Very Frequent User
    • May 31, 1989
    • 113

    Mr. Joe Lucia, Could You Help Me Verify Some Part Numbers?

    Joe,

    I am working on an early 1968 427/435hp with A.I.R., body build date: Sept. 5, 1967.

    This car is missing the entire A.I.R. system, and I wanted to replace it (and some other parts) with all of the
    original part numbers. I already have a restored A.I.R. pump. My sources are the "1968 Corvette Assembly Manual" and the "Corvette Parts Book".

    A.I.R. Pump Pulley .... #3925522
    Water Pump Pulley .... #3883235 or #3848904
    Water Pump "Add-on" Pulley ... #3765427
    Water Pump ... #3977630
    Fan Clutch ... #3916141
    5-Blade Fan ... #3740523 or #3883235
    Crankshaft Pulley ... #3850838 or 3860010

    I pulled the crankshaft pulley the other night, and it's not even a Corvette P/N,
    although it did come off of a Chevrolet big block. I'm not sure that the 5-blade
    fan is stamped with a part number.

    Any help you can provide would be appreciated.
    Thanks for all you do!

    Russ Trotter
    NCRS #15044
  • Joe L.
    Beyond Control Poster
    • February 1, 1988
    • 43193

    #2
    Re: Mr. Joe Lucia, Could You Help Me Verify Some Part Numbers?

    Originally posted by Russ Trotter (15044)
    Joe,

    I am working on an early 1968 427/435hp with A.I.R., body build date: Sept. 5, 1967.

    This car is missing the entire A.I.R. system, and I wanted to replace it (and some other parts) with all of the
    original part numbers. I already have a restored A.I.R. pump. My sources are the "1968 Corvette Assembly Manual" and the "Corvette Parts Book".

    A.I.R. Pump Pulley .... #3925522
    Water Pump Pulley .... #3883235 or #3848904
    Water Pump "Add-on" Pulley ... #3765427
    Water Pump ... #3977630
    Fan Clutch ... #3916141
    5-Blade Fan ... #3740523 or #3883235
    Crankshaft Pulley ... #3850838 or 3860010

    I pulled the crankshaft pulley the other night, and it's not even a Corvette P/N,
    although it did come off of a Chevrolet big block. I'm not sure that the 5-blade
    fan is stamped with a part number.

    Any help you can provide would be appreciated.
    Thanks for all you do!

    Russ Trotter
    NCRS #15044

    Russ-------

    A.I.R. Pump Pulley .... #3925522---this is correct; discontinued without supersession in October, 1979

    Water Pump Pulley .... #3883235 or #3848904-----1st design used 2 groove pulley GM #3848904 with 1 groove add-on pulley GM #3883235. 2nd design used 3 groove pulley GM #3888366 with no add-on pulley. 3883235 was discontinued without supersession in July, 1984. GM #3848904 was discontinued in September 1972 and replaced by GM #3995641

    Water Pump "Add-on" Pulley ... #3765427------ 3765427 not used; this is a small block pulley; see above

    Water Pump ... #3977630----This part number did not even exist in 1968. Waterpump used was GM #3876173 or 3927564. No matter which as both are identical, these numbers appear nowhere on the pump and both use casting GM #3856284 (which is cast on the pump). Both waterpumps were discontinued in 1969.

    Fan Clutch ... #3916141-----Most likely this was the fan clutch used. It was discontinued about 10 years ago. Later production MIGHT have used GM #3937771 which is an entirely different configuration. It was discontinued in February, 1980 and replaced for SERVICE by the 3916141.

    5-Blade Fan ... #3740523 or #3883235----3740523 is a spacer, not a fan. It MAY have been used with 1st design waterpump pulleys. 3883235 is the 1 groove add-on pulley, not a fan blade assembly. Fan blade assembly used was GM #3888366. This is a 5 blade assembly with no part number stamped on it. It was discontinued in April, 1971 and replaced by 7 blade fan GM #3955182

    Crankshaft Pulley ... #3850838 or 3860010----GM #3850838 is a small block crankshaft pulley not used on big blocks. GM #3860010 is the harmonic balancer used for your engine, not a pulley. The pulley used for your engine was supposed to be a stamped steel pulley of GM #3921923. However, I believe that most, if not all, 1968 L-71 were fitted with a cast iron pulley of GM #3863108. Both of these pulleys are functionally interchangeable. Both are discontinued.

    I do not know when 1st design pieces changed to 2nd design.
    In Appreciation of John Hinckley

    Comment

    • Russ T.
      Very Frequent User
      • May 31, 1989
      • 113

      #3
      Re: Mr. Joe Lucia, Could You Help Me Verify Some Part Numbers?

      Thanks Joe for your invaluable assistance.
      Some of these parts are getting pretty expensive, and I
      want to be sure that I'm buying the correct ones.

      Russ Trotter

      Comment

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

        #4
        Re: Mr. Joe Lucia, Could You Help Me Verify Some Part Numbers?

        Russ------


        One thing to keep in mind: the 1968 1st design 2 groove waterpump pulley was 5.89" OD. The 1968 2nd design 3 groove pulley was 5.5" OD. This means that the 2nd design pulley drives the waterpump and fan at a faster speed for any given engine speed. The faster speed and consequent better cooling is not a bad thing for a big block Corvette.
        In Appreciation of John Hinckley

        Comment

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