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Header Bolt Length

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Old Apr 10, 2012 | 08:48 PM
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Default Header Bolt Length

I am going to get Stage-8 Header bolts. They come in either 1" or 3/4". I measured the depth of the hole in my Dart heads and they are 3/4" deep. My Flowtech headers came with 3/4 long bolts. But the header flange to the head is over 1/4" with the gasket, so I have a little over an inch with everything. (This is a loose measurement. I dont know how much the gasket will compress)

So should I stick with the 3/4" long bolts or will the 1" bolts work. The one inch bolts will give me the most bite, as long as they dont bottom out. Or would 1/2" of bite work in Aluminum. I am running Dart SHP Aluminum heads if that matters.

-X
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Old Apr 10, 2012 | 09:06 PM
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Do you have aluminum heads?
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Old Apr 10, 2012 | 09:09 PM
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Yep. Aluminum Dart SHP's.
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Old Apr 10, 2012 | 09:24 PM
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bottoming out is the real problem...i am convinced most people who continually have leaky headers have this problem because of bolts bottoming out and they dont know it
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Old Apr 10, 2012 | 11:10 PM
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Originally Posted by Xterrable
Yep. Aluminum Dart SHP's.
Then you need ARP 3/8ths nut studs. It makes R&R ing headers a breeze and use FelPro blue metal header gaskets for your port type.

Summit Racing has them. I posted the number before. I just redid my motor with AFR heads and hooker S/C that I have had for years

Grade 8 and locking are just junk and you don't want to strip the head threads

I have posted pic's on my home page if you click my name

I just looked at my CF home page that was nearly 5 years ago I do have fender flares that cover those big slicks

Last edited by gkull; Apr 10, 2012 at 11:16 PM.
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Old Apr 11, 2012 | 07:32 PM
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Do studs (well, the nuts) tend to stay put better than bolts?
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Old Apr 11, 2012 | 09:49 PM
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There are several different advantages to using studs, but in this case I think the main one is that you practically eliminate the risk of stripping a thread in the head. Aluminum is pretty soft, and a stud engages every thread in the hole, spreading the load out. Even if you have to remove the studs to get the header on or off, they are still better. If you insist on using bolts, just measure the depth of the hole, and the thickness of the flange, and add the two measurements together. The thickness of the gasket and a washer under the bolt head will keep it from bottoming out. With a bolt, you really want to engage as much thread as possible without bottoming out.


Keep the shiny side up!
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Old Apr 12, 2012 | 12:33 AM
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You locktight the studs in and never remove them. It makes taking the headers on and off very easy.

I've has headers on motors for many years and never had to touch the nuts. A little dab of permitex red high temp keeps the nuts from backing off
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