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ARP studs too big for head?

Posted by adollarwodbnice, May 2, 2010

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  1. adollarwodbnice

    adollarwodbnice Proven Member

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    Mays Landing, New Jersey
    Well, after literally a full month of having the head off I finally got my buddy's tap and die set and I was able to get the last ARP head stud in. I go to drop the head on and it goes on maybe an inch....

    I tried several different ways to make this work and it just would not go down. So, I took my spare head that's completely bare and it dropped down perfectly. Pulled a stud out to check tolerances and sure enough my bolt holes are too narrow for the ARPs... even stock bolts I had on were kinda tight.

    The spare head I had was from either a 90 or 91 but I have no idea what my head came off of.

    Does this mean I need to get a different set of ARPs? Do they make different thicknesses? I'm tempted to go with stock bolts because they will fit but I don't wanna blow another head gasket.

    Not really sure what to do at this point since I just spent 250 to have my built head decked, hot tanked, fully reassembled to proper specs, pressure tested, and is completely ready to be dropped on...
     

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  2. nuclearr

    nuclearr Proven Member

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    Joined Jun 22, 2004
    Slidell, Louisiana
    Sounds like you may have a 7 bolt head. I would take it to a machine shop and ream out the bolt holes in the head. I think the 7 bolts are 1mm smaller than the 6 bolts.
     
    My DSM:
    1996 Mitsubishi Eclipse Spyder GST

    Street Build

      manual
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  3. adollarwodbnice

    adollarwodbnice Proven Member

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    Now this kinda puzzles me... does this mean I have a 7 bolt block too... couldn't I just get 7 bolt studs so I don't have to drill out the head... like I said I just spent 250 to have this head properly machined and it essentially doesn't fit because the bolts are too big....
     
  4. nuclearr

    nuclearr Proven Member

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    Joined Jun 22, 2004
    Slidell, Louisiana
    NO. If your studs are for a 6 bolt and they threaded in then you have a 6-bolt block. 7 bolt studs are smaller and will strip out or pull out under boost.
     
    My DSM:
    1996 Mitsubishi Eclipse Spyder GST

    Street Build

      manual
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  5. adollarwodbnice

    adollarwodbnice Proven Member

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    Mays Landing, New Jersey
    UGH... things you wish you ####in' knew like a month ago....

    Thanks....
     
  6. donniekak

    donniekak DSM Wiseman

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    Surprise, Arizona
    Run a 1/2" drill through them, from the deck side.
     
    My DSM:
    1991 Eagle Talon TSi AWD

    Street Build

      manual
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  7. adollarwodbnice

    adollarwodbnice Proven Member

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    Mays Landing, New Jersey
    I honestly don't own a drill that could do this task nor do I want the responsibility of screwing up my head. Gonna call my machine shop that did the head and see if they can drill all the holes out for me...

    Could someone explain how a 7 bolt head would end up on a 6 bolt block and also how the head bolts worked on it?

    EDIT: I guess they didn't really work on it technically because it blew a head gasket.
     
  8. 90moneypit

    90moneypit Proven Member

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    Joined Mar 2, 2010
    treefall, Washington
    Some people like the larger ports on a 7 bolt head so they put them on 6 bolts. Another possibility is someone wanted a 6 bolt bottom end in their 2g without the rest of the hassles. :idontknow: An easy way to check this is to compare the size and shape of the head in question with another 1g 6 bolt.
     
  9. IHeartMyHonda

    IHeartMyHonda Proven Member

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    murfreesboro, Tennessee
    7 bolts actually have smaller ports than 6 bolts. it helps with spool time and throttle response because there is less volume in the manifold and block to fill before air gets into the cylinders. thats why some people run them on their 6 bolt blocks.
     
    My DSM:
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  10. adollarwodbnice

    adollarwodbnice Proven Member

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    Mays Landing, New Jersey
    Well, no matter what the guy who did this decided to do it for he obviously didn't do it right... it really doesn't make much sense... for instance if the head bolts are already head bolts for a 6 bolt and they fit through the 7 bolt head you would think the same size 6 bolt studs would work too... they're REALLY close just not close enough. I'm starting to remember why I loved the 3/S so much... almost everything is interchangeable from heads to blocks to body parts... DSMs are a little more complicated.

    Has anyone ever had a 7 bolt head drilled out to accept 6 bolt studs? Is there any sort of advantage that a 7 bolt head has over a 6 bolt... i've compared both the 7 and 6 bolt heads I have and I see no differences at all.
     
  11. BogusSVO

    BogusSVO Proven Member

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  12. adollarwodbnice

    adollarwodbnice Proven Member

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    Thanks for the tip... don't think i'm gonna do that but if I get bad tick or odd pressure i'll consider it haha.

    Just got the head back from the machine shop... hopefully I can get this sucker on finally!
     
  13. BogusSVO

    BogusSVO Proven Member

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    Pensacola, Florida
    its your hla tic to deal with LOL

    what is the thickness of your head?
     
  14. adollarwodbnice

    adollarwodbnice Proven Member

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    Mays Landing, New Jersey
    If you mean the bolt holes they are now 12mm... I just got done torquing the head down and all just need to push my tensioner back in and set the timing and it's good to go! :D

    This car should be alot of fun so hopefully I don't screw anything up... i've done several timing belts on a 3000gt and had no problems but i've never worked on a DSM before.
     
  15. BogusSVO

    BogusSVO Proven Member

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    Pensacola, Florida
    the thickness of the head is measured from the valve cover rail to the head gasket surface
     
  16. FLASH1970

    FLASH1970 Proven Member

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    Lake Geneva, Wisconsin
    Do it once and do it right. Listen to BogusSVO. I am DEFINITELY doing the oil port mod when I do the 2g head on a 6 bolt block. Also, Check to make sure your intake ports on the head match the manifold. You might have a 1g intake manifold on a 2g head which will rob you of power because the ports are shaped different.
     
    My DSM:
    FLASH1970 1992 Eagle Talon TSi AWD

    50trim   manual
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  17. adollarwodbnice

    adollarwodbnice Proven Member

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    Joined Mar 9, 2010
    Mays Landing, New Jersey
    Technically I am doing it right... my friend has built several DSMs and had 0 issues without having to do any extra grinding on the head and assured me it's fine so i'm not worried about it. There's still many things to replace and double check before I can even start it so I have time to look over the whole car before cranking her over. Also, intake side of the head was ported and polished so that's been done for a while... I made sure gaskets and holes matched when I put the intake manifold on so there's no issues there.
     
  18. KazooGS-T

    KazooGS-T Proven Member

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    Joined Aug 29, 2006
    Ridgeland, Mississippi
    Post a picture of the intake ports on your head, we'll know within two seconds if it's a 7bolt head or a 6bolt
     
    My DSM:
    1998 Mitsubishi Eclipse GSX

    Street Build

      manual
    1993 Eagle Talon TSi AWD

    12.700 @ 115.000 MPH
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  19. adollarwodbnice

    adollarwodbnice Proven Member

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    Joined Mar 9, 2010
    Mays Landing, New Jersey
    Sorry I guess I should update the first post... the car is all back together just finished putting everything back in just need to do timing belt and it's good to go.
     

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