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Technical Equal-ish length salt flat style headers

Discussion in 'Traditional Hot Rods' started by Choppedcoupe, Apr 8, 2026 at 8:19 AM.

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  1. Choppedcoupe
    Joined: Oct 17, 2016
    Posts: 264

    Choppedcoupe
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    I’m currently running cast Ram-horn style exhaust manifolds on my 1931 ford coupe on 1932 frame with SBC. I’m planning to set the car up for drag racing and am considering changing my exhaust to a tube header. If I can’t fit a tube header inside the frame, I’m considering my options for going outside the frame. I certainly like the look of a salt flat style “header” exiting at the cowl, but most of those 40s/50s style headers that I see are basically a log manifold. Do any of you know of a source for a equalish length header that exits near the cowl yet remains up high, without d****** down over the radius rods. I may be looking at a custom header, but I wanted to check the brain trust first.
     
  2. 19Eddy30
    Joined: Mar 27, 2011
    Posts: 4,504

    19Eddy30
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    from VA

  3. Equipped28
    Joined: Mar 30, 2007
    Posts: 639

    Equipped28
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    The word “Lakes” headers always makes me laugh when they are the most un lakes thing ever when all they are bolt on do dad that makes your car slower.
    If you really want a cowl exit header you will have more benefit with a shotgun style of each primary having some length to it.

    The lakes headers cause a huge amount of back pressure and restriction and when you hear a car with them on they sound asthmatic, I would try to push for a full length tube header, I managed to fit 1 3/4” primary headers with long collectors onto a SBC in a model A ch***is. This car would run low 11’s all day long and i attributed that to actually having real headers.

    there is a interesting engine masters video testing various novelty headers it’s worth a look.

    IMG_0526.jpeg
     
    Deutscher likes this.
  4. willys36
    Joined: May 6, 2006
    Posts: 3,327

    willys36
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    Equal length is only a benefit if the length is tuned to the speed the engine is designed to run. For a street driven car running at 1,200rpm you want a 34" primary tube. For a 8,000rpm dragster, 16" is more desirable. For a Sonic cruiser I would be looking for a good looking header, more akin to the function of a manifold.

    Chrysler did a bunch of work on intake and exhaust design and developed this formula to estimate optimal primary tube length.

    L=(850×(180+BBDC))/RPM

    Where:
    • L = primary tube length (inches)
    • BBDC = exhaust valve opening timing (degrees before bottom dead center)
    • RPM = target engine speed
    • 850 = empirical constant (based on speed of sound in hot exhaust gas ≈ 1300–1700 ft/s)
    That constant changes to a lower number in intake manifold design since the speed of sound is slower in cooler gas.
     
    Last edited: Apr 8, 2026 at 5:57 PM
    AHotRod, GuyW, Deutscher and 2 others like this.
  5. 19Eddy30
    Joined: Mar 27, 2011
    Posts: 4,504

    19Eddy30
    Member
    from VA

    Op has Two threads
    Op plans a 383 with 200 of spray,
    a mid 383 should be 500
    I would look into 1-7/8 they are not true with out Stahl pattern, & I would use angle plug header's even not angle head used
    Lemons , pics on other thread for in rail
     
    Last edited: Apr 9, 2026 at 4:08 AM
  6. Choppedcoupe
    Joined: Oct 17, 2016
    Posts: 264

    Choppedcoupe
    Member

    What is the advantage of angle-plug headers? Is it for spark plug clearance?
     
  7. Choppedcoupe
    Joined: Oct 17, 2016
    Posts: 264

    Choppedcoupe
    Member


    Can you send more photos of your engine bay (especially the headers and related clearances) and perhaps the model number or application for the headers you used? Your info is super valuable to me along with your experiences.
     
  8. 19Eddy30
    Joined: Mar 27, 2011
    Posts: 4,504

    19Eddy30
    Member
    from VA

    Angle plug headers will give more Clarence for spark plugs on non angle plug heads
     
  9. dirt car
    Joined: Jun 26, 2010
    Posts: 1,711

    dirt car
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    from nebraska

    May need to break out the welder would like to find a pair of flathead outside the frame rail headers similar to my avatar
     
  10. willys36
    Joined: May 6, 2006
    Posts: 3,327

    willys36
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    That's always my approach!!
     
  11. AHotRod
    Joined: Jul 27, 2001
    Posts: 12,426

    AHotRod
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    rod1 and Just Gary like this.
  12. 1971BB427
    Joined: Mar 6, 2010
    Posts: 9,962

    1971BB427
    Member
    from Oregon

    One of the best header designs around is the old Y type where two cylinders are Y together, then the final two pipes join into a collector. They fit in tight spaces, and tests have shown they flow as well as 4 equal tubes.
     
  13. dirt car
    Joined: Jun 26, 2010
    Posts: 1,711

    dirt car
    Member
    from nebraska

    Thanks, I tried the Schoenfeld web site, didn't see any Flathead offerings
     
  14. Equipped28
    Joined: Mar 30, 2007
    Posts: 639

    Equipped28
    Member

    I don’t have a huge amount of photos, but here they were when I fabricated them, As I say 1 3/4 primary’s into a 3” collector roughly around 20” long, then blanking plates so it can run through a system. Motor was a 383 although stock 4” bore as the block was new so a 377” in reality, nothing crazy for cam or heads. Vac secondary carb, tri Chevy rear ended with with a welded 3.77 diff. And would run 11’s consistently, best was a 11.21 @ 118 and I would drive it to the track and back

    IMG_0542.jpeg IMG_0543.jpeg IMG_0544.jpeg IMG_0545.jpeg
     
    GuyW and 4274SPEED like this.

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