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Help me identify my engine?

Discussion in '1965-1970 Shelby Mustang GT350 & GT500' started by radojko, Dec 12, 2016.

  1. radojko

    radojko Member

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    Mornin' all!

    So, I'm trying to familiarize myself with my newly-acquired 68 GT500. The engine has me puzzled, so I'm hoping for some enlightenment here.

    I have the original build sheet, a partial copy of which I've attached.

    My limited understanding of the encoding of the sheet is that the engine is supposed to be a 428PI. Based on the pretty comprehensive documentation that I have for the car, I'm 98% confident that its the original engine. Now I just need to confirm.

    Was there a "standard" 428 engine for 68 GT500's? If so, which flavor should it be? How can I identify it - is it possible to do so without actually pulling the engine? I tried to find a casting date on the block, but haven't been successful as of yet.

    A pretty knowledgeable friend told me that the PI should be externally balanced and should have a counterweight that's visible on the flywheel. Is that true? I have a C6 transmission, which has the "wagon wheel" flywheel - is that correct? If there should be a counterweight, am I correct in assuming that it would be visible on the forward face of the flywheel?

    Questions, questions, questions. :confused:

    Many thanks,
    -Bob-
     

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  2. radojko

    radojko Member

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    Oh, and one more (unrelated) question. :whistle:

    According to the build sheet, the axle is supposed to be a 3.00:1. There's no tag on the pumpkin. How would I go about identifying which axle it is...?

    Thanks again,
    -Bob-
     
  3. Coralsnake

    Coralsnake Well-Known Member

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    The only engine used in a production 1968 Shelby is the 428 Police Interceptor.

    The date code is located between the oil filter and the block. There is very likely to be a stamped serial number on the back face of the block or head.

    Automatic cars would use a flex plate not a flywheel.

    You can jack up the car and turn the rear wheel. The ratio for every rotation should be 3 to 1 with the driveshaft.
     

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