Bore heads for larger headbolts or stud/insert ?
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Northstar Engines and System Technical Discussion Discussion, Bore heads for larger headbolts or stud/insert ? in Cadillac Engine Technical Discussion; Local shop use larger headbolts and drills/taps block to accept them. Enlarges holes in head to fit. Did not say ...
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    stoveguyy is offline Cadillac Owners Connoisseur
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    Bore heads for larger headbolts or stud/insert ?

    Local shop use larger headbolts and drills/taps block to accept them. Enlarges holes in head to fit. Did not say what they do for alignment dowels? Seems to me dowels are pretty thin wall? Says bolts are "custom"? I think they are just sourced from another brand/make vehicle? If GM went with simple threaded bolt holes in block, what's wrong with tapping the next size larger? Ya, I know there is a limit to bolt diameter?

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    Re: Headbolts

    Nothing. That's essentially what "Bigserts" are and what Jake's studs are as well. Not sure about CCC's, but I suspect they are as well. It's not so much the diameter as much as the coarser thread pitch.

    P.S.
    I believe the same holds true for Norms NS300L inserts.

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    stoveguyy is offline Cadillac Owners Connoisseur
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    A big sert has larger OD threads than a standard sert but still uses stock headbolts? The studs I see here are stepped? Larger diameter into block but standard diameter up thru head? I was wondering about how much clearance work u can do on head thru holes? Not many folks here talk about enlarging head thru holes

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    Submariner409's Avatar
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    Re: Headbolts

    Don't try to bore out the cylinder head bolt holes to accept larger bolts. There are very good reasons why GM, Cadillac, Jake, Tim, Joe, Norm, TimeFastener, and a host of others make and use the proper studs and inserts.

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    RippyPartsDept's Avatar
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    Re: Headbolts

    Quote Originally Posted by Submariner409 View Post
    Don't try to bore out the cylinder head bolt holes to accept larger bolts. There are very good reasons why GM, Cadillac, Jake, Tim, Joe, Norm, TimeFastener, and a host of others make and use the proper studs and inserts.
    .......................
    Chris Heath (RippyPartsDept) is an ASE Certified GM Parts Consultant at
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    stoveguyy is offline Cadillac Owners Connoisseur
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    I know the head thru hole is bigger than bolt. Bolt is M11. Is hole 12mm? I am not planning on trying larger bolts. Just reporting on local shops process.

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    Re: Bore for larger headbolts or stud/insert ?

    Quote Originally Posted by stoveguyy View Post
    A big sert has larger OD threads than a standard sert but still uses stock headbolts?
    Correct.


    The studs I see here are stepped? Larger diameter into block but standard diameter up thru head?
    Correct again.


    I was wondering about how much clearance work u can do on head thru holes? Not many folks here talk about enlarging head thru holes
    The holes through the head? No need for that. The gripping is done at the block threads. Those are the threads that failed. Those are the threads that are made larger and coarser. There is simply no reason (or advantage that I can think of) for a larger diameter bolt or stud through the head.

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    stoveguyy is offline Cadillac Owners Connoisseur
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    The shop does over counter fix or drive in-turn key work. He says they do in car jobs so they must be handy.

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    Re: Bore for larger headbolts or stud/insert ?

    Quote Originally Posted by stoveguyy View Post
    so they must be handy.
    or sloppy/cut corners
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    Re: Bore for larger headbolts or stud/insert ?

    The shop is mistaken - No such Northstar block work as "over the counter" or "turnkey" - too many hoops to jump through.

    Studs and inserts remove the failed/corroded bolt threads, replace them with threaded steel parts ..................

    Here - see if you can figure out what an "insert" really does, then what block studs do .................

    http://www.huhnsolutions.com/

    http://www.carrollcustomcadillac.com/Pages/default.aspx

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    stoveguyy is offline Cadillac Owners Connoisseur
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    They said they can do ANY repair. U bring in motor alone. They fix it. Or u can use ur motor as core and they give u another. That is what I meant by over the counter. Turnkey means u drop off car.

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    mmidyette is offline Cadillac Owners Member
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    Re: Bore heads for larger headbolts or stud/insert ?

    Just a guess, but, if you dramatically change the diameter of the section of the bolt (non threaded area) that needs to expand and contract as the engine goes through its heat cycles, will you not also have to recalculate the initial torque values during installation to allow for this change? If you try to put a larger diameter bolt section up through to the head, I think that it would "stretch" differently than those selected by the GM engineers, causing new problems.

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    Re: Bore heads for larger headbolts or stud/insert ?

    BTSOM! Now you're getting into engineering and metallurgy. WAAAY beyond my knowledge.

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    Manic Mechanic is offline Cadillac Owners Fanatic
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    Re: Bore heads for larger headbolts or stud/insert ?

    I've recently repaired my Northstar car using Carrol's stud kit. I haven't mentioned it yet but fitting the heads down onto the installed studs was a PITA. I've been "handy" with metal objects since I was a kid and do this for a living quite well but despite all my best efforts the studs weren't "perfectly vertical" (Tim Carroll) after free hand drilling just like he does in his videos. Most were close enough but a few on each side required some minor bending with the hoist's jack handle slipped over them for leverage. Even after all were pretty strait up it was still next to impossible to get the heads down. Every time I got them somewhat started there were metal shavings being developed by the studs scraping against the head holes. So after several attempts and some thought I started drilling out the head itself to make more room for the stud to pass through. First drill was actually the same diameter of the studs and it removed some material in spots but not all the way through. I attribute this to corrosion and shifting of the metal over the 130K in service under pressure. The head still wouldn't slide down as cleanly as I like so I went the next 1/64th over. Same thing so I went another 64th and that was enough to get the head to slide onto the deck reasonably, it could be set down and lifted with a slight drag and wiggle. I just got it running last week and have only put about 130 miles on it with only one short WOT blast through a yellow light this morning but so far so good. At the 1/32 level of head hole enlargement there was not an issue and the stud nuts and washers still blanketed the hole. It was not an issue with the alignment dowels because it was still way under that diameter step.

    BTW I'm not complaining about Tim's kit because it is an aftermarket repair part and it's doing what I need it to do with some mild massaging but I would love to see an uncut video of him drilling, tapping, studding, and then just sliding some un-drilled heads down onto the decks. It's not going to happen. His prices, service, and personal technical advice over the phone were great.

    Vernon

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    PaleAle is offline Cadillac Owners Fanatic
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    Re: Bore heads for larger headbolts or stud/insert ?

    Stoveguyy,
    If the shop you're referring to is in Mahtomedi, they are legit. They have done a lot of them. I had them do a 98 SLS for me a while back before I learned to do it myself. A friends Mom bought the car and put 43000 miles on it before she sold it over a year ago. They give a 1 year unlimited mileage warranty.
    I've only done a dozen of them and haven't attempted one in the car yet. I'm tempted to try it though. If you add up removing and reinstalling the cradle, recharging the AC, bleeding the brakes, etc. It might be worth a try, especially on a Deville where the front cross brace unbolts. Unfortunately, my next one is a 2002 STS but I might try it anyway. I can always pull it if I run out of patience.

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