Why Do Header Bolts Come loose?
Thread Starter
Race Director
Joined: Aug 2000
Posts: 14,130
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Cruise-In II Veteran
Why Do Header Bolts Come loose?
I was just wondering...I dont run headers and theres been a few times Im hearing certain headers(bolts) would come loose.Whats the main reason for that?I guess why Im asking is the GM shorties on my 86 has never come loose,even after remove/install about 4 times already and using anti-seize on the threads.They always stayed tight.Im running the shorties through a no pre-cats Y pipe and if its a heat cycle issue,there must be a big difference between Long tubes and short ones and the size of the Y pipe?
Just curious...If I get long tube headers someday,would like to know ahead of time what to expect and the fixes.
:cheers:
Just curious...If I get long tube headers someday,would like to know ahead of time what to expect and the fixes.
:cheers:
Team Owner
Joined: Mar 2000
Posts: 83,383
Likes: 87
From: Boston, MA
Re: Why Do Header Bolts Come loose? (Bill's86Coupe)
My guess is that it has to do with how some header gaskets react to the first few heat cycles. They could shrink/warp/whatever and give the most minute amount of clearences allowing the bolts to vibrate slightly and work themselves free.
Thread Starter
Race Director
Joined: Aug 2000
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Cruise-In II Veteran
Re: Why Do Header Bolts Come loose? (scorp508)
Hey scorp,
Thats a good idea...may be just what it is....Ive been running the Fel Pro one piece exhaust manifold gasket and they seem to work great with the factory pieces.Theyre like foil gaskets or something.Whats interesting though,after removal of the bolts,the antiseize seems to have "gel" up and maybe thats helped to keep the bolts from vibing loose or something.if anything,they came off super easy too.Just wondering,even though Im not running true headers.Thanks for the info.
:)
Thats a good idea...may be just what it is....Ive been running the Fel Pro one piece exhaust manifold gasket and they seem to work great with the factory pieces.Theyre like foil gaskets or something.Whats interesting though,after removal of the bolts,the antiseize seems to have "gel" up and maybe thats helped to keep the bolts from vibing loose or something.if anything,they came off super easy too.Just wondering,even though Im not running true headers.Thanks for the info.
:)
Drifting
Joined: May 2003
Posts: 1,979
Likes: 48
From: Lakeport CA
Re: Why Do Header Bolts Come loose? (Bill's86Coupe)
I've found that it has to do with the way the bolts/mounting plate are set up. And yes, it has to do with the heating/cooling. Stock has those nice tube/extensions that the bolt tightens down onto. That distance seems to keep them from loosening up. My TPIS long tubes have the same mount system & I've never had a bit of problem either. Now my old V8 Vega had Don Hardy headers & I went through 2 sets over the 20 years I owned the car, always had to keep checking them until I bought some of those Stage 8 locking bolts, really nice system which I also use on my Durango headers, they stay tight too.
:cheers:
:cheers:
Le Mans Master
Joined: Apr 2000
Posts: 5,713
Likes: 105
From: Manassas VA
Re: Why Do Header Bolts Come loose? (Trog)
I just ordered a set of the EM headers and merle said to use the stage 8 bolts. Kinda expensive, $50.00 but will be well worth it if they are maintance free afterwards.
Drifting
Joined: Jul 2001
Posts: 1,296
Likes: 0
From: Largo Florida
Re: Why Do Header Bolts Come loose? (93 ragtop)
I used to have the bolts get loose but that stopped when I wrapped the bolts with silcone glue. I figure it helps absorb the vibration and holds it too.
Melting Slicks
Joined: Mar 2001
Posts: 2,149
Likes: 303
From: Timra, Sweden
Re: Why Do Header Bolts Come loose? (Trog)
The stock design with long bolts and 'tube extensions' on the header flange works well. The longer bolt can stretch more when heating/cooling without getting loose.
You get the most problems with a weak flange and short bolts.
I installed stage8 locking bolts with my header just to be sure.
You get the most problems with a weak flange and short bolts.
I installed stage8 locking bolts with my header just to be sure.
Race Director
Joined: Aug 2000
Posts: 11,506
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From: Vancouver,Wa.
Re: Why Do Header Bolts Come loose? (Bill's86Coupe)
I have never had one come loose on my vette yet. Here is what I do. Hooker 2149, Felpro #1404, Arp 3/4 12 point header bolts and some anti sieze. Tighten them down to you get one vein on the forehead to pop out. Start the car and run here for a while, Come back and let her cool and retighten. Use the anti sieze on the bolts.
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Race Director
Joined: Sep 2000
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From: The Top of Utah
Re: Why Do Header Bolts Come loose? (Corvette0096)
Tighten them down to you get one vein on the forehead to pop out.
RACE ON!!!
Melting Slicks
Joined: Mar 2001
Posts: 3,365
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From: Lake Villa IL
Cruise-In IV Veteran
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St. Jude Contributor
Re: Why Do Header Bolts Come loose? (CFI-EFI)
:iagree:
When you first install them, it's a pain. But after a few cycles and retightening, they'll stick and the problem should go away. It is a freaking pain, though.
Popular Hot Rodding just ran an article about some header bolts that come in two pieces. You have an outer shell, which is the threads, and then an inner core that tightens down into the shell, forcing the threads out into the hole. The outer shell uses a normal socket. The inner core is tightened using an allen wrench. Looked interesting. I'm not sure of the cost.
When you first install them, it's a pain. But after a few cycles and retightening, they'll stick and the problem should go away. It is a freaking pain, though.
Popular Hot Rodding just ran an article about some header bolts that come in two pieces. You have an outer shell, which is the threads, and then an inner core that tightens down into the shell, forcing the threads out into the hole. The outer shell uses a normal socket. The inner core is tightened using an allen wrench. Looked interesting. I'm not sure of the cost.
Le Mans Master
Joined: Jan 2003
Posts: 8,596
Likes: 19
From: Portland Oregon
Re: Why Do Header Bolts Come loose? (Bill's86Coupe)
I use ARP 6 point SS bolts with square wire lock washers under the bolt heads. After a few days of heating and cooling I retorque the bolts and after that I check them once a year. To date using the square wire lock washers I have yet to have a bolt work loose.
I also use Fel-Pro exhaust gaskets as well. Below is a close up picture of a bolt on my engine with Exotic Muscle headers, you can see the square wire lock washer uner the bolt head. I don't like them weird snap ring locking devices on my header bolts as they are a real PITA to install and remove.
I also use Fel-Pro exhaust gaskets as well. Below is a close up picture of a bolt on my engine with Exotic Muscle headers, you can see the square wire lock washer uner the bolt head. I don't like them weird snap ring locking devices on my header bolts as they are a real PITA to install and remove.
Thread Starter
Race Director
Joined: Aug 2000
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Re: Why Do Header Bolts Come loose? (tjwong)
Thanks again for all the replies....now another observation I made....with the GM shorties,you can lay the manifolds flat on the gasket areas and it wont rock back and forth like its off or crooked...and it doesnt have a full flat bracket/flange...could this be a factor?I noticed LT headers have a full flange or bracket that goes all the way cross the pipes to mount to the heads to make it a flat contact area...I wonder if LT headers had those parts cut out,would it then seal the first time like stock manifolds do?
Just wondering...without the long flange or bracket,theres no extra heat cycles to pass back and forth to the middle from the side tubes to where the bolts would go.Just for thought.
:crazy: :cheers:
Just wondering...without the long flange or bracket,theres no extra heat cycles to pass back and forth to the middle from the side tubes to where the bolts would go.Just for thought.
:crazy: :cheers:
