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Technical Header Performance on Flatheads?

Discussion in 'Traditional Hot Rods' started by blowby, Sep 4, 2013.

  1. blowby
    Joined: Dec 27, 2012
    Posts: 6,597

    blowby
    Member
    from Nicasio Ca

    Getting ready to weld up some exhaust and wondering about headers. I'm familiar with the performance advantage of headers on OHVs but wondering if the performance benefit is worth the usual inconveniences on a flathead. Seems like by the time the exhaust makes it way across, down and through the block some of the advantages headers offer might be reduced. Talkin' a street car with mufflers, stock cam.
     
  2. headers w/dual exhaust will help a bit with all else stock.
     
  3. blowby
    Joined: Dec 27, 2012
    Posts: 6,597

    blowby
    Member
    from Nicasio Ca

    Thanks, I should have added it will have duals and glass packs either way, manifolds or headers.
     
  4. JeffB2
    Joined: Dec 18, 2006
    Posts: 8,263

    JeffB2
    Member
    from Phoenix,AZ

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  5. blowby
    Joined: Dec 27, 2012
    Posts: 6,597

    blowby
    Member
    from Nicasio Ca

    Good point, thanks Jeff.
     
  6. not sure who fab'd these under car tubes....got them back in the 80's from an old guy....hoping Jeff will fab up a new set...we need to find out if they will clear a stock wish bone or what....




    both 1.jpg

    IMAG0005.jpg
     
  7. Thor1
    Joined: Jun 6, 2005
    Posts: 1,426

    Thor1
    ALLIANCE MEMBER

    stillrunners,

    If those headers would fit on my stock '47 Ford Tudor I would love to buy a set if somebody would fab some up.

    Thor
     
  8. CGkidd
    Joined: Mar 2, 2002
    Posts: 2,842

    CGkidd
    ALLIANCE MEMBER

    Those are some cool looking headers.
     
  9. that would be Jeff in Dallas....
     
  10. If you read JWLs fantastic book, you will find that the difference in performance on a basically stock engine between stock manifolds and headers is minimal, certainly not worth the expense or hassle. This should be mandatory reading for anyone with a flathead. Hundreds of dyno pulls, all documented.
     
  11. 40FordGuy
    Joined: Mar 24, 2008
    Posts: 2,908

    40FordGuy
    Member

    Even a small gain is good....... I'm a believer !

    4TTRUK
     
  12. flatmotor40
    Joined: Apr 14, 2010
    Posts: 534

    flatmotor40
    Member
    from georgia

    Tatom engines make a set of full length tube header for flatheads and they are great
     
  13. revkev6
    Joined: Jun 13, 2006
    Posts: 3,351

    revkev6
    Member
    from ma


    I disagree. the flathead has 12+" of the exhaust gasses running together, trying to split them back up after the fact will not help you at all. once the pulses are combined you cannot split them again....
     
  14. I second JWLs book as he has done many, many dyno pulls on a flattie in various stages of hop up...
     
  15. vinnymac44
    Joined: May 16, 2008
    Posts: 142

    vinnymac44
    Member
    from W. Oregon

    A small gain would be a good thing. I vote to run em. And what ever you do, leave the mufflers off! Flatties are not so loud that you can't run em with straight pipes.
     
  16. As already stated, headers don't help much on a flathead because the restriction is in the block, no down stream in the exhaust system. If you are looking for power, a quality porting job is much more critical then headers.

    Good Luck
     
  17. flatheadpete
    Joined: Oct 29, 2003
    Posts: 9,708

    flatheadpete
    Member
    from Burton, MI

    A small gain on a flathead is actually a big gain! Every little bit helps.
     
  18. blowby
    Joined: Dec 27, 2012
    Posts: 6,597

    blowby
    Member
    from Nicasio Ca

    Mine is a 60hp, and I'm pretty sure I read that somebody made a divider you could shove in the block.
     
  19. JeffB2
    Joined: Dec 18, 2006
    Posts: 8,263

    JeffB2
    Member
    from Phoenix,AZ

    Well since we let the Genie out of the bottle here is an interesting discussion:http://www.fordbarn.com/forum/showthread.php?t=23241 John Bradley ran port dividers aka "splitters" guess he might know a thing or two about flatheads.;) Notice the headers in this test: http://www.youtube.com/watch?v=dYH1TgYhx84 and this one:http://www.youtube.com/watch?v=_-IevaW2lLY Both are pulling some good numbers.
     
    Last edited: Sep 6, 2013
  20. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 21,682

    Bruce Lancaster
    Member Emeritus

    The splitters in the article mentioning Bradley are a completely different concept creating a barrier up between the valves, not dividing the common port all the way.
    Olds type ports, similar to those on some British engines, were separate except for the last bit, and on those engines a carefully shaped baffle from paired headers effectively separated the cylinders all the way.
     
  21. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 21,682

    Bruce Lancaster
    Member Emeritus

    Here's a link to one excellent post:

    http://www.jalopyjournal.com/forum/showthread.php?t=332905&highlight=exhaust&showall=1

    I'm pretty sure that if you use Vergil in advanced search you'll find some more of this cutaway info. Flatdog was one of the truly great developers and his posts will churn up some good brain food.
    FD believed in heavily slanting the end port exits for a smooth transition from the angle of the last part of the port.
    Ron H describes a totally different approach, cutting ports toward ends of block and adding a fabricated baffle, in effect eliminating the last curve and making a straight shot out.
     
  22. blowby
    Joined: Dec 27, 2012
    Posts: 6,597

    blowby
    Member
    from Nicasio Ca

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