Northstar headbolt spacing/ pattern
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Northstar Engines and System Technical Discussion Discussion, Northstar headbolt spacing/ pattern in Cadillac Engine Technical Discussion; I know the measurements on the block deck for the head bolts of a 4.9L are 3.5in by approx 4.4in ...
  1. #1
    John.Westlock is offline Cadillac Owners Member
    Automobile(s): 72 Coupe Deville, 95 Eldorado, 72 Skylark, 54 GMC XM215
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    Northstar headbolt spacing/ pattern

    I know the measurements on the block deck for the head bolts of a 4.9L are 3.5in by approx 4.4in and rectangular but does anyone have a a 4.6L block they could measure? In my manual they look to be rectangular but I can find no measurements for the bolt spacing on the deck. Are they all the same from 93 to 2010 or are the head bolts spaced different? I did google it and searched on the site but can't find anything.

    I did come across some Land Rover forum where the guys actually measured the bore spacing to see if they would work on a custom project but apparently the bore spacing wasn't what they needed so they didn't bother with the bolt spacing. I guess some people are willing to try to adapt heads from one make to another- that or just desperate. At least the intake ports are horizontal and easier to adapt to if you ever want to without worrying about all the angles. I've owned the BB Caddys for some time now and thought they were great but these little Nothstars are pretty neat in their own right. Thanks in advance.

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  3. #2
    89falcon is offline Cadillac Owners Fanatic
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    Re: Northstar headbolt spacing/ pattern

    Quote Originally Posted by John.Westlock View Post
    I know the measurements on the block deck for the head bolts of a 4.9L are 3.5in by approx 4.4in and rectangular but does anyone have a a 4.6L block they could measure? In my manual they look to be rectangular but I can find no measurements for the bolt spacing on the deck. Are they all the same from 93 to 2010 or are the head bolts spaced different? I did google it and searched on the site but can't find anything.

    I did come across some Land Rover forum where the guys actually measured the bore spacing to see if they would work on a custom project but apparently the bore spacing wasn't what they needed so they didn't bother with the bolt spacing. I guess some people are willing to try to adapt heads from one make to another- that or just desperate. At least the intake ports are horizontal and easier to adapt to if you ever want to without worrying about all the angles. I've owned the BB Caddys for some time now and thought they were great but these little Nothstars are pretty neat in their own right. Thanks in advance.
    I believe the bore spacing is 4" in the N*....and not a match to anything you'd want to use it on.....I think it's the same as the yamaha/volvo V8....which already has 4V heads.

  4. #3
    John.Westlock is offline Cadillac Owners Member
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    Thread Starter

    Re: Northstar headbolt spacing/ pattern

    Thanks 89Falcon but I really am interested in the bolt spacing/ pattern not the bore center. My Eldorado only has 30K on it so I would rather not take the heads off just yet.

    I was just amazed that some people take the heads off of totally different engines and bolt them on- those Rover guys must be pretty desperate. If someone knows or has the heads off already I would appreciate it if someone could let me know.

  5. #4
    89falcon is offline Cadillac Owners Fanatic
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    Re: Northstar headbolt spacing/ pattern

    Quote Originally Posted by John.Westlock View Post
    Thanks 89Falcon but I really am interested in the bolt spacing/ pattern not the bore center. My Eldorado only has 30K on it so I would rather not take the heads off just yet.

    I was just amazed that some people take the heads off of totally different engines and bolt them on- those Rover guys must be pretty desperate. If someone knows or has the heads off already I would appreciate it if someone could let me know.
    OK...now I'm a little confused about your question. If you are looking to put the heads on to a different block, the bores must line up. If not.....why do you need to know what the bolt spacing is? Maybe a little insight into what you plan on doing would help us anser your question.

  6. #5
    John.Westlock is offline Cadillac Owners Member
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    Thread Starter

    Re: Northstar headbolt spacing/ pattern

    I am looking at some inserts for prventative maintence but don't like the way the jig is designed that comes with it. I know other guys have used it and had good results but I don't like the idea of bolting it done with one bolt and the sliding adjustment. I would prefer one that uses all four holes- more stable, etc.

    If someone has the measurements I would really appreaciate it as I don't want to pull the heads off and have the car sitting there/ disabled while the parts are being shipped. I plan on doing it with the engine in the car and want to be able to push the car out of the way if I need to. I know everyone says its harder but for my situation it is easier. Being a former mechanic and working on other cars much of my life it shouldn't be a problem for me.

    So does anyone have the measurements?
    Thanks.

  7. #6
    89falcon is offline Cadillac Owners Fanatic
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    Re: Northstar headbolt spacing/ pattern

    Quote Originally Posted by John.Westlock View Post
    I am looking at some inserts for prventative maintence but don't like the way the jig is designed that comes with it. I know other guys have used it and had good results but I don't like the idea of bolting it done with one bolt and the sliding adjustment. I would prefer one that uses all four holes- more stable, etc.

    If someone has the measurements I would really appreaciate it as I don't want to pull the heads off and have the car sitting there/ disabled while the parts are being shipped. I plan on doing it with the engine in the car and want to be able to push the car out of the way if I need to. I know everyone says its harder but for my situation it is easier. Being a former mechanic and working on other cars much of my life it shouldn't be a problem for me.

    So does anyone have the measurements?
    Thanks.
    Copy.....

    a quicker solution may be to find someone who still has a "jig" for Jakes N* performance studs and use it (buy or rent/borrow). It's already drilled.

    I know I'm not answering your question with the specs....just offering up a potential solution.

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