how many times can a crank get turned

Discussion in 'High Performance Modifications' started by ripcurl329, Nov 21, 2010.

  1. ripcurl329

    ripcurl329 Veteran Member

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    How many times can a crank get turned?

    I have an 1182 steel crank and it has been turned already...

    but when is it too much and it starts to take away from performance?
     
  2. Rick WI

    Rick WI Veteran Member

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    When you can't get the correct size replacement bearing
     
  3. Rich Schmidt

    Rich Schmidt Veteran Member

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    Guys cut cranks WAY down. Some guys will turn the crank you have all the way down to small journal rod size to reduce bearing speed in high rpm engines,or even offset grind them down to the small journal size to increase stroke. My personal opnion is to have the journals hardened after any time you have the crank turned.
     
  4. z28rod

    z28rod Veteran Member

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    good advise on high hp engines..
     
  5. Rick WI

    Rick WI Veteran Member

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    How do you re-harden a forged crank? How does the machining change the forge? I see a lot of cranks go from the grinding machine to the engine with no issues at all. Nitride treated, different story.
     
  6. NYH1

    NYH1 Veteran Member

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    What is Nitride treated??
     
  7. Cardinal

    Cardinal Veteran Member Lifetime Gold Member

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    As said, usually can be turned till you can't find bearings to fit it. A "standard" undersized maximim would be .030" on a 350 large journal crank unless you consider that you can also grind it to a small journal Chevy crank diameter which would also include .030" undersized bearing for that too.


    They also use a cryogenic freezing process to harden them. It creats less stress on the metal yet hardens it.
     
    Last edited: Nov 22, 2010
  8. ripcurl329

    ripcurl329 Veteran Member

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    Thanks for all the info.

    I know my crank had already been turned to .030". The machinist said that he would check to see if it is straight and that he could turn it... but at the same time he also stated when i asked about how far you could turned it down " you wont drive it a million miles a day"... so that made me think it was starting to take away from performance and durability.
     
  9. Cardinal

    Cardinal Veteran Member Lifetime Gold Member

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    IF it's already turned .030", seriously think of what the concequences are if the crank fails (broken block, bent rods, etc.). IMHO, cut to the chase and buy a new standard forged crank.
     
  10. jakeshoe

    jakeshoe Veteran Member Lifetime Gold Member

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    You can get .050 under bearings for a SBC. It doesn't weaken the crank, if properly machined it will actually be stronger.
     

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