• Welcome to SVTPerformance!

GT350 Header bolt torque spec

Discussion in '2015+ Shelby GT350 Mustang' started by 662, Jul 3, 2019.

  1. 662

    662 Active Member Established Member

    Messages:
    237
    Joined:
    Mar 31, 2014
    Location:
    Houston
    What are you guys torqueing header bolts to? Anyone use Stage 8 locking bolts and do you apply anti-seize?

    I've watched a few youtubes looking for torque spec and not found any. What I learned is it's a PIA and so glad the motor is out of the car for this. I'm already in love with the R sound so I hope it gets better not worse, not sure its possible.

    And the Kook's look so good, seems like Ford would have used long tubes in the first place. With the engine out I'm staring at some type 4-3-1 manifold, shared with the CPC 2020 and certainly not cheap, but compared to the long tubes it just looks like it would better suit a CPC where long tubes are all matched length and should manage the symmetric pulses most simply.
     
    Last edited: Jul 3, 2019
  2. ANGREY

    ANGREY Active Member Established Member

    Messages:
    536
    Joined:
    Oct 24, 2017
    1) I did my swap with the motor in the car, which is a giant PITA.
    2) I used Stage 8, with the locking tabs, but the problem is the stage 8 bolt head sizes are small, so they don't have the coverage/bearing area as the kooks bolts, so you'll have to check to ensure that they give enough bearing on the kooks flanges as you're comfortable with. On my ARH, the flanges are slotted (to ease installation) and there was only a marginal amount of coverage I was comfortable with across the flange opening.
    3) I'd be cautious using anti-seize if you're not going to use the stage 8 with locking tabs. I didn't have a torque spec either, so I torqued them as much as I felt safe with the confidence that the motor vibrations wouldn't be able to work them loose. Anti-seize is great if you have a spec'd torque you're comfortable with that won't vibe loose. I guess what I'm saying is anti-seize works both ways, ensures you don't bind on the way in, but also means that threads are slippery so head to flange bond will need to be greater than any NVH concerns.
    4) Another part of the equation is the gaskets. If you have a good gasket, it can go a LONG way into ensuring you don't have leaks and don't need to torque the bolts to death to keep them from backing out. Hopefully you bought new ones (or they come with the Kooks) and you're not trying to reuse the OEM ones.
     
  3. 1987GN

    1987GN New Member

    Messages:
    8
    Joined:
    May 24, 2019
    Location:
    Connecicut
    You should use anti seize on aluminum threads. It keeps the bolts from "micro welding" if that happens you will likely rip out the threads on removal.
     
  4. 662

    662 Active Member Established Member

    Messages:
    237
    Joined:
    Mar 31, 2014
    Location:
    Houston
    Thanks for the guidance guys. I've looked around and not found any actual spec data, so I think I am going to use the stage 8 locking bolts that came with headers and use anti seize and torque starting from center cylinders first to 11ftlbs then to 26ftlbs and lock it down...

    Oh, and I have one more question on the exhaust, it came with fancy clamps so you don't have to weld, but I am wondering if it's better to weld any of the joints on the x-pipe section and to the mufflers.

    Opinions and feedback mucho appreciated.
    Cheers
     
    Last edited: Jul 10, 2019
  5. 662

    662 Active Member Established Member

    Messages:
    237
    Joined:
    Mar 31, 2014
    Location:
    Houston
    Knowing a torque spec turns out not to be as useful as one would expect... It's impossible to get a socket on all the header bolts and we needed to come up with a method and choose to torque down the accessible bolts closest to center and then using a wrench on others and work outward, judging the wrench torque compared to torqued ones.

    IMG_2726.PNG

    Access to some of the bolts was difficult and I would not have wanted to do it in the car.
     
    DeathvalleySC and DAVESVT2000 like this.
  6. DeathvalleySC

    DeathvalleySC Member Established Member

    Messages:
    67
    Joined:
    Jun 20, 2018
    Location:
    South Carolina
    I agree. It’s impossible to torque them. I used the Stage 8 header bolts that lock. They work great. They came with the kooks system.


    Sent from my iPhone using the svtperformance.com mobile app
     

Share This Page