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Technical Can I just shape and chamfer these Fenton header outlets with a half round file?

Discussion in 'The Hokey Ass Message Board' started by oilslinger53, Sep 3, 2019.

  1. oilslinger53
    Joined: Apr 17, 2007
    Posts: 2,500

    oilslinger53
    Member
    from covina CA

    Going through my engine, cleaning it up, fixing some minor things, and switching to dual exhaust, and just noticed these outlets are flat, and this one isn’t quite round. I know I can get them pretty close by hand, but how perfect do they need to be? do they need to be machines? Donut seals are pretty flexible, right? IMG_6813.JPG


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  2. LM14
    Joined: Dec 18, 2009
    Posts: 1,937

    LM14
    Member Emeritus
    from Iowa

    I would concentrate on the head pipe sealing area. As long as the head pipe is slightly larger than the manifold you are good. Don't want the pipe smaller than the manifold. Making it round might make you feel better but I doubt you would see 1HP difference.
    SPark
     
  3. Mike VV
    Joined: Sep 28, 2010
    Posts: 2,482

    Mike VV
    Member
    from SoCal

    What he said...
    IF...the pipe that bolts to that flange is larger, then some grinding (not filing) MIGHT be in order.
    IF the casting is thick enough..!

    Mike
     
  4. gimpyshotrods
    Joined: May 20, 2009
    Posts: 19,171

    gimpyshotrods
    ALLIANCE MEMBER

    If you port-match, you will likely pick up 0.0067hp!

    But seriously, if this is a 216, 236, or 261, switching to a dual exhaust system is likely to cause you to lose power (by defeating proper scavenging), not gain, so don't obsess over slight port mismatch.
     

  5. oldiron 440
    Joined: Dec 12, 2018
    Posts: 2,550

    oldiron 440
    Member

    The key is to find thirty ways to find one horsepower.
    That's why some builders always make more power.
     
    Last edited: Sep 4, 2019
    WB69 and Texas Webb like this.
  6. Elcohaulic
    Joined: Dec 27, 2017
    Posts: 2,598

    Elcohaulic
    Member

    Yes, file it so its slightly bigger than the port..
     
    brigrat and WB69 like this.
  7. jimmy six
    Joined: Mar 21, 2006
    Posts: 10,279

    jimmy six
    ALLIANCE MEMBER

    I would. Set a gasket on it and scribe a line so you can make it round. It doesn't need to be out to the gasket line. I've even used those small sanding wheels to knock of some of the roughness of the casting on them.
     
  8. dreracecar
    Joined: Aug 27, 2009
    Posts: 3,218

    dreracecar
    Member
    from so-cal

    you would never know if you didn't make before and after dyno pulls
     
  9. oilslinger53
    Joined: Apr 17, 2007
    Posts: 2,500

    oilslinger53
    Member
    from covina CA

    ???
    I just don’t want it to leak. I’m not trying to scrape power!


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