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  1. #1
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    Default Holden V8 1/2" Mains Conversion

    Just wondering if anyone has a sticky on a good "how to" convert the 7/16" mains on a Holden V8 to the 1/2" Clevo style ARP studs??
    I know TK has mentioned it a few times but I can't find it. Cheers

  2. #2
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    May not have been a sticky, I can't find it either!

    It's pretty simple:

    Bolt up main caps with the stock bolts, make sure you get the thrust on the rear cap aligned.
    Remove the bolts on one side.
    Use the bolt holes as a drill guide to drill for the 1/2" tap - 27/64" drill.
    Remember which side you've drill (mark it with a texta on the cap), remove the caps & drill the bolt holes on that side to 13mm on a drill press.
    Bolt the caps back up with the remaining bolts.
    Use the 13mm drilled bolt holes as a tap guide to tap the 1/2" UNC threads - you'll need a long tap, often you won't be able to go full depth before you hit the cap, but as long as you've got at least 4-5 threads that's enough.
    Remove the caps & finish tapping the threads.
    Now you can use the 1/2" studs in that side & repeat the process for the other side.

    Last step is to take it to a good machine shop & get it line honed.
    I'm not on here much any more - don't bother PM'ing me, chances are I won't read it, just call me on 08 8376 9540 if you need to get hold of me or email knight28@optusnet.com.au, phone is better!

  3. #3
    been here .......too long Smitty2's Avatar
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    Quote Originally Posted by 46Crab View Post
    Just wondering if anyone has a sticky on a good "how to" convert the 7/16" mains on a Holden V8 to the 1/2" Clevo style ARP studs??
    I know TK has mentioned it a few times but I can't find it. Cheers
    don't remember any sticky on this topic
    but given TKs reply... it is now
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  4. #4
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    When I do the next one I'll get some pics up, may be a couple of months tho.
    I'm not on here much any more - don't bother PM'ing me, chances are I won't read it, just call me on 08 8376 9540 if you need to get hold of me or email knight28@optusnet.com.au, phone is better!

  5. #5
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    Quote Originally Posted by TK383 View Post
    May not have been a sticky, I can't find it either!

    It's pretty simple:

    Bolt up main caps with the stock bolts, make sure you get the thrust on the rear cap aligned.
    Remove the bolts on one side.
    Use the bolt holes as a drill guide to drill for the 1/2" tap - 27/64" drill.
    Remember which side you've drill (mark it with a texta on the cap), remove the caps & drill the bolt holes on that side to 13mm on a drill press.
    Bolt the caps back up with the remaining bolts.
    Use the 13mm drilled bolt holes as a tap guide to tap the 1/2" UNC threads - you'll need a long tap, often you won't be able to go full depth before you hit the cap, but as long as you've got at least 4-5 threads that's enough.
    Remove the caps & finish tapping the threads.
    Now you can use the 1/2" studs in that side & repeat the process for the other side.

    Last step is to take it to a good machine shop & get it line honed.
    Thanks TK, much appreciated. Some pics on the next one you do would be awesome.

  6. #6
    Part of the furniture Tim304's Avatar
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  7. #7
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    Quote Originally Posted by TK383 View Post
    When I do the next one I'll get some pics up, may be a couple of months tho.
    When you next do one of the 1/2" mains conversions can you please add the ARP P/N you use. Cheers

  8. #8
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    clevo studs I think.

  9. #9
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    Quote Originally Posted by guy incognito View Post
    clevo studs I think.
    ARP 154-5404 are the Cleveland studs that worked for me.

  10. #10
    Do you ever leave? 308HG's Avatar
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    whats the math on this?
    say 355 at xxxxrpm?
    383 at xxxxrpm?
    when do you step up to 4 bolt?
    p.b. 10;78@ 123.19mph. never late with a 308

  11. #11
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    When the caps start walking.
    I wouldn't push a 355 much past 6500 on 2 bolts and a 383, less.
    With 1/2" studs you could stretch it a bit higher.

  12. #12
    Do you ever leave? cava454's Avatar
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    Default Holden V8 1/2" Mains Conversion

    I always thought 1/2 weakens the integrity of the block?

    I used to turn my 304 to 7200. Using Gm factory mains. No ARP. Never let me down

    Granted I never opened it up to check for cap walk.

  13. #13
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    Quote Originally Posted by cava454 View Post
    I always thought 1/2 weakens the integrity of the block?

    I used to turn my 304 to 7200. Using Gm factory mains. No ARP. Never let me down

    Granted I never opened it up to check for cap walk.
    exactly
    total waste of time and won't stop walk but increases the chances of cracking your block around the webbing
    we took over the maintenance of a small block that is turned very hard
    it had 1/2" inner studs 7/16" outer studs and girdle when we took over the engine work
    at first we thought it was tune related but even with a perfect tune we could still see fretting on the cap and block faces on some of the caps
    we doweled all five caps and never saw it again
    cap walk is not cause by vertical force but horizontal
    if a cap is going to walk with 70LB of clamping force then an extra 30 LB isn't going to make that much difference
    ONE STOP MOTORSPORT SHOP - engine building and development - tuning and complete fuel systems-- latest dyno dynamics dyno --click the link to see our facebook page https://www.facebook.com/pages/Zok-R...9505334?ref=hl

  14. #14
    Do you ever leave? cava454's Avatar
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    Quote Originally Posted by zok race carbs View Post
    exactly
    total waste of time and won't stop walk but increases the chances of cracking your block around the webbing
    we took over the maintenance of a small block that is turned very hard
    it had 1/2" inner studs 7/16" outer studs and girdle when we took over the engine work
    at first we thought it was tune related but even with a perfect tune we could still see fretting on the cap and block faces on some of the caps
    we doweled all five caps and never saw it again
    cap walk is not cause by vertical force but horizontal
    if a cap is going to walk with 70LB of clamping force then an extra 30 LB isn't going to make that much difference
    Can you install the main on angle? I know the ls has 4 top and 2 thru the side.

  15. #15
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    Quote Originally Posted by cava454 View Post
    Can you install the main on angle? I know the ls has 4 top and 2 thru the side.
    what do you mean mate main on angle
    ONE STOP MOTORSPORT SHOP - engine building and development - tuning and complete fuel systems-- latest dyno dynamics dyno --click the link to see our facebook page https://www.facebook.com/pages/Zok-R...9505334?ref=hl

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