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Technical BBC headers to Hemi flanges

Discussion in 'The Hokey Ass Message Board' started by 53 hemi, May 15, 2020.

  1. 53 hemi
    Joined: Jan 8, 2009
    Posts: 465

    53 hemi
    Member

    I'm looking for fenderwell headers to fit a Chrysler Hemi and pickings are pretty slim. It looks like BBC port spacing is pretty close - has anyone adapted BBC headers to Hemi flanges?

    Sent from my SM-G950U using The H.A.M.B. mobile app
     
  2. squirrel
    Joined: Sep 23, 2004
    Posts: 46,099

    squirrel
    Member

    I ended up making my own fenderwell headers for my BBC. Then made a pair of them for my (late) Hemi.

    It's fun, give it a try.
     
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  3. earlymopar
    Joined: Feb 26, 2007
    Posts: 1,171

    earlymopar
    Member


    Agreed. Making custom headers (for me) was the most gratifying part of one of my previous builds. On my latest build I took a different path and adapted Ford headers to a Mopar "A" series small block given the exhaust port spacing was close between the two engines. Rather than re-flange the "Ford" headers for the Mopar, I machined adapters to fit the Mopar block to fit the Ford headers.

    - EM
     
    Last edited: May 16, 2020
    Just Gary likes this.
  4. This was mentioned not long ago in another thread .
    It was stated that it was fairly straightforward,,,,worked well .

    Seems like it was 73 RR that mentioned it,,,,but don’t hold me to that .

    I’ve read a lot of threads in the last few months .

    Tommy
     
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  5. wvenfield
    Joined: Nov 23, 2006
    Posts: 5,074

    wvenfield
    Member

    We built our set of headers also but next time if there was something I could adapt I would do that. LOL

    It's not all that complicated but it was time consuming. (but it was the first time doing it.)
     
    '51 Norm likes this.
  6. dreracecar
    Joined: Aug 27, 2009
    Posts: 3,005

    dreracecar
    Member
    from so-cal

    anytime you try to intermingle two species, you are asking for more trouble and work then to just start from scratch
     
    lippy likes this.
  7. Mike Colemire
    Joined: May 18, 2013
    Posts: 1,210

    Mike Colemire
    Member

    I'd like to do fenderwells on my plymouth sedan with BBC, if I had a tig, I'd build my own.
     
  8. seb fontana
    Joined: Sep 1, 2005
    Posts: 6,459

    seb fontana
    Member
    from ct

    Mig will work, at least to "tack up" then can take them to a welder?
     
  9. squirrel
    Joined: Sep 23, 2004
    Posts: 46,099

    squirrel
    Member

    I did my first mostly with a torch.....like they used to do back in the old days. It still works, you know. I spent a while thinking about how to build them, and two days actually building them.
     
    Desoto291Hemi likes this.
  10. This is what happens when you take Chevy headers and make them fit a Dodge

    20200515_184047.jpg
     
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  11. greybeard360
    Joined: Feb 28, 2008
    Posts: 1,465

    greybeard360
    Member

    The port spacing may be close but the angle the headers bolt to the head is a lot different between the two. You would have a lot more work trying to make them fit vs. scratch building the whole header.
     
  12. wvenfield
    Joined: Nov 23, 2006
    Posts: 5,074

    wvenfield
    Member

    As noted, you do not need a Tig. We did ours with a mig. Are the welds "pretty dimes"? No, but that wasn't the point. To hell with car shows and people bitching about the welds. It was about putting pieces of metal together that would hold together and do the job.

    Even then we used a quite old Mig welder that would on occasion spit and spurt. Not because it was more "traditonal" but because it's what we had. Are all the welds "pretty"? No. Did we grind here and there? Yes. Are they coming apart? Never.
     
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  13. seb fontana
    Joined: Sep 1, 2005
    Posts: 6,459

    seb fontana
    Member
    from ct

    ^^Do it^^
     
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  14. wvenfield
    Joined: Nov 23, 2006
    Posts: 5,074

    wvenfield
    Member

    Everything was Mig welded. I am NOT dismissing the talent of those who can make really pretty welds. It's a great talent and impressive. Only saying that just because you can't is not a reason to not do it.

    I have a friend that is an amazing welder. I could have paid him (if you notice there are tabs welded to the aluminum radiator, I did trade him something for those welds) but then, that wasn't the point of the build.

    Pontiac Gasser 3.jpg
     
  15. blowby
    Joined: Dec 27, 2012
    Posts: 6,592

    blowby
    Member
    from Nicasio Ca

    What I've always wondered is how you weld the pipes in the center of the collector?
     
  16. gimpyshotrods
    Joined: May 20, 2009
    Posts: 17,139

    gimpyshotrods
    ALLIANCE MEMBER

    You weld them before you slip the collector on.
    [​IMG]
     
  17. squirrel
    Joined: Sep 23, 2004
    Posts: 46,099

    squirrel
    Member

    yup, a little almost square piece goes right in the middle, between the 4 tubes
     
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  18. Last edited: May 16, 2020
  19. squirrel
    Joined: Sep 23, 2004
    Posts: 46,099

    squirrel
    Member

    why you want to use a torch....gives those nice old fashioned looking seams between sections of tube, without the raised lump that MIG makes, and without looking too high tech, like TIG does.

    [​IMG]

    Also, gotta braze the fillet between the flange and tube, like Stahl used to do when they built headers.

    Of course, these suggestions only apply if you are trying to build a traditional car.
     
    willys36 and Just Gary like this.
  20. I agree with lots of the above. Home made headers is in the strike zone of most backyard builders. You don't need TIG unless you are using stainless and MIG is not a very good app. It is fast but good looking quality welds are very hard to achieve with that system. Headers are made to be oxy/acetylene gas welded. And it is FUN trust me. I use a MIG to weld the tubes to the flanges from the inside, weld the tubes with torch and brass brazed fillets on the outside of the tube/flange joint. Use a 3' gas welding rod to make a pattern for the path of each tube. Added benefit is 3' is about the optimum length of a header tube for street headers, so use the whole length of the rod for each tube for equal length headers. Headers are sensitive to length and diameter changes, not sensitive to turns so bend them wherever necessary. Just buy 8 or 10 180deg tubing bends and cut them to appropriate sections per your welding rod pattern and weld them up.

    A good way to mock up the header is make a temporary mount of wood to hold the collector, set the chassis/engine to running height and make the pattern to fit between the two. Here is that setup for my Mysterion build.

    engine header assembly.JPG jaj 11-20.JPG
    jaj 11-25.JPG

    Here are some examples of my header builds.

    Finished Mysterion
    vertical.jpg

    My first attempt at headers for my 331 hemi. 18 yrs old. Circa 1967
    Early  B&W 1.jpg

    Final set of Willys headers circa 1995. Planning on making another set sort of like the first set above. Want to replace the 331 heads with big valve, big port truck heads first.
    March_Meet_sunday_tim_166.jpg

    Set for a 230ci straight Chevy 6
    headers.jpg Engine closeup..JPG

    Set for '42 Willys pickup. Had to work around steering. Equal length.
    7-25-2013 6-47-58 AM.jpg
     
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  21. 53 hemi
    Joined: Jan 8, 2009
    Posts: 465

    53 hemi
    Member

  22. squirrel
    Joined: Sep 23, 2004
    Posts: 46,099

    squirrel
    Member

    I used some aluminum rod, it cost more, but less bendy. I also made a jig to simulate the collector. I bent each rod with another jig I made to give it the same bend radius as the actual U bends I bought. Having all this prep work done, made the fabrication go pretty quickly.

    headers15.jpg
     

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