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Thread: Main studs

  1. #1
    Mitsu booster
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    Main studs

    So i bought a built common block that was done awhile ago, and well they did the main studs with the Non-common block studs and im a little skeptical on running it. I have the common block studs already and was just curious to know if i could just remove the 6 inners and change them to the correct ones without having a issue? Whats everyone's thoughts?

  2. #2
    Slugmobile & MeanMini Caretaker Turbo Mopar Contributor wheming's Avatar
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    Re: Main studs

    I'm curious to know what is different about the main studs?
    Wayne H.

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  3. #3
    Supporting Member II Turbo Mopar Contributor ilovethecane69's Avatar
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    Re: Main studs

    As long as the mains were checked/honed with studs in place, I do not see an issue swapping the inner 6 out for the longer CB studs.

  4. #4
    Mitsu booster
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    Re: Main studs

    Thats what i figured, but wanted to get more experienced advice as well.

  5. #5
    Supporting Member II Turbo Mopar Contributor zin's Avatar
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    Re: Main studs

    If the clamping force is the same (same dia., same torque, same washer/nut diameter) the distortion should be the same, and so no problem.

    HOWEVER, if you are going to worry about the precision of having the right studs (a good thing in my book!), I'd have a machine shop check the bore alignment/roundness with the new studs in place...

    The only problem with doing so is the possibility of finding something out of spec, and that being the first domino in the line of block prep... I say that because, if you're going to be very precise, the studs will distort the bore, just as a torqued cylinder head (or torque plate) will, and so throw things off...

    Of course, this reminds me of a saying a former Top Fuel mechanic used to say: "If you're not going to do something about it, don't bother checking..."

    In reality, if this isn't going to be a maximum effort piece, it probably won't matter if things are off a little, just won't last as long/well.

    Best of luck!

    Mike
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  6. #6
    turbo addict
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    Re: Main studs

    Wayne, the center 6 threaded holes are threaded deeper on the common blocks. Studs are designed to lightly bottom out in block. Using early block studs on a CB would cause them to float in block rather than bottom out. A long time ago I listed the part #'s one would need for the common blocks. I emailed this same info to the vendors so they could stock the correct parts for their customers. Told ARP to list this in their catalog about a dozen times, but each time it just fell on deaf ears. Part #'s are listed here;
    http://www.turbododge.com/forums/f4/...lock-main.html

    Original poster, IMO you should be okay just replacing the studs with the correct ones. Hopefully the block was align bored and honed when your engine was built. Many people have ran their CB engines with the early block studs with no ill effect. Not saying I recommend that or endorse that, but just throwing that out there. If you really want to know for certain, you could check journal measurements with gauges or Plastigage using both studs to see if there is any negligible difference in distortion in the journal. I doubt you will find any.
    Todd

  7. #7
    Slugmobile & MeanMini Caretaker Turbo Mopar Contributor wheming's Avatar
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    Re: Main studs

    Thanks Todd, good info!
    I went around with ARP on their headstuds listings. Same deaf ears.
    Wayne H.

    '91 Dodge Spirit ES 2.5L turbo 5spd
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  8. #8
    Hybrid booster
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    Re: Main studs

    Pull out the crank, torque the main caps using the new CB studs, and check the journal bore for round.
    The inside mic needed can be had for less than you may think.
    In other words, check it out yourself. No worries.


    Sent from my iPhone using Tapatalk

  9. #9
    Moderator Turbo Mopar Staff Force Fed Mopar's Avatar
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    Re: Main studs

    I doubt it would ever make any difference to just leave them

    Rob M.
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  10. #10
    Hybrid booster
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    Re: Main studs

    I think I agree ^^^
    But if you want to be completely thorough, and you're concerned there might be the smallest of differences, it's not necessarily an impossible task to check it out.


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  11. #11
    Mitsu booster
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    Re: Main studs

    Quote Originally Posted by Force Fed Mopar View Post
    I doubt it would ever make any difference to just leave them
    It would probably be fine, But there's like a total of 4 threads actually being using for clamping force. Plus i got the correct studs to change them out.

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