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Thread: crank numbers?

  1. #1
    Speedin' Ian
    pulled the pan off the new motor and got some numbers off the crank and pistons. Anyone know what they mean? The motor is supposed to be a 427
    crank=804816NF (I think these were the numbers, hard to read)
    pistons=242-99

  2. #2
    Speedin' Ian
    Also can anyone tell me what the torque rating is on the main caps? It is a two bolt main with studs

  3. #3
    Speedin' Ian
    Here's a pic of one of the bearings.
    http://www.***boat.com/image_center/...40_IMG-med.JPG

  4. #4
    Fiat48
    Torque specs link is in the gear head sticky. ARP PDF.
    By the number, sounds like the crank is aftermarket. Also looks to have a large radius which also indicates aftermarket. Piston number probably means nothing as far as identifying pistons. No evidence of main cap walking indicates this old girl is a virgin to high horsepower, which is a nice find.
    Be sure to use proper torque with specified lube when you look up torque specs.

  5. #5
    Speedin' Ian
    WHat do you mean by large radius?

  6. #6
    Fiat48
    The radius ground into the edges of the main journal. Could be just your photo. Nothing bad here, looks good.
    If you want to check something, then check and see if there is a wide forging mark front of the crankshaft. To make sure it's a forged crankshaft and not a cast.
    http://www.***boat.com/image_center/...Forged-med.JPG

  7. #7
    GofastRacer
    Looks like a cast crank to me!..

  8. #8
    Fiat48
    Originally posted by GofastRacer
    Looks like a cast crank to me!..
    Has that "dull" look...could very well be.

  9. #9
    GofastRacer
    I lightened the pic up and I didn't see any forging marks?...

  10. #10
    Speedin' Ian
    I'm pretty sure it is a cast crank which is no big deal, we're not planning on running it too hard. The numbers I gave you could be wrong, they were hard to read, the 8 could be 3 and any of the other numbers could be wrong. I'm sure it's a GM crank because it has GM stamped on it, but it has been balanced.

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