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Hot Rods Buick Straight 8 compound carburetion

Discussion in 'The Hokey Ass Message Board' started by strait8, May 24, 2019.

  1. strait8
    Joined: Jun 11, 2014
    Posts: 131

    strait8
    Member
    from Skokie, IL

    I am hoping to one day put compound carb system on 51 Special with 263 straight 8. I have the dual intake manifold from a 41' but no exhaust manifold or risers for it. I am trying to decide if I could run the stock dual carb manifold but utilize headers? I am thinking I will have a problem since there will be no heat riser although my current single carb system riser is currently stuck open and it does not pose much of any issue. I do have (2) risers each from separate single intake systems but it does not look as though they would adapt easily to the dual system. I know that the stock manifold systems split the carb barrels so that they feed front and back cylinders. I am wondering if fabricating an intake with mandrel bends and balance tube along with headers would be easier or better? Thinking of using 2 Strombergs (4 bolt) because that is what I have. I am posting a video of a guy who looks to have successfully done it using I think 2 Holleys. Anybody our there done this?
     
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  2. kbgreen
    Joined: Jan 12, 2014
    Posts: 326

    kbgreen
    Member

    The original design was for the engine to run on the front carb only until the progressive linkage kicked in the rear carb. The rear car has did not have a choke either. I'll include a couple links to the AACA/Buick site where you can see a discussion from one guy that built an exhaust manifold but used the stock intake. Then, if I can find it, another guy discussed making both carbs active synchronously which is technically a better set up as the front carb on stock set up would not be feed all cylinders equally. That guy reported more power and better fuel mileage.

    Matt Harwood building an exhaust manifold, different engine, but worth seeing the problems he worked around:
    https://forums.aaca.org/topic/299008-1941-limited-limousine/page/2/

    Greg Johnson's post on the alternate linkage for the two carb set up:
    https://forums.aaca.org/topic/326771-putzing-with-1941-42-dual-carb-parts/
     
    harpo1313 likes this.
  3. kbgreen
    Joined: Jan 12, 2014
    Posts: 326

    kbgreen
    Member

    Oh yeah, and this is very important: DO NOT SAY ANYTHING ABOUT NON FACTORY MODS! you'll get crucified. There are some that appreciate modification efforts, but a couple guys is all it takes for a mounted campaign to have you blessed out.
     
  4. firstinsteele
    Joined: Jun 13, 2013
    Posts: 916

    firstinsteele
    Member

    If you get "blessed out ", ask the mods to move you to the modified forum. Or just go there. I will talk to you there.

    Ben
     
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  5. Hnstray
    Joined: Aug 23, 2009
    Posts: 10,325

    Hnstray
    ALLIANCE MEMBER
    from Quincy, IL

    Ben, I think the warning about 'non'factory mods' is in regard to AACA, not the HAMB
     
  6. firstinsteele
    Joined: Jun 13, 2013
    Posts: 916

    firstinsteele
    Member

     
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  7. RichFox
    Joined: Dec 3, 2006
    Posts: 9,574

    RichFox
    ALLIANCE MEMBER

    img163.JPG The rear carb is actually more like the secondarys on a four barrel. It also had an air valve under it. If you wanted to run two carbs together, you need two front carbs.
     
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  8. Tim
    Joined: Mar 2, 2001
    Posts: 9,362

    Tim
    Member
    from Raytown Mo

    You should be fine with headers. Plenty of inline motors that came with a heat riser set up have ditched them and been just fine.
     
  9. Stooge
    Joined: Sep 9, 2015
    Posts: 272

    Stooge
    ALLIANCE MEMBER

    Again, tread lightly, but theres a current thread in the pre war buick section about someone putzing around with compound carburetors on a straight 8 https://forums.aaca.org/topic/326771-putzing-with-1941-42-dual-carb-parts/

    My 320's intake set up is just very early mocked up and i havent started the header until i get the engine in. Going to be a direct/ nonprogressive linkage, 4 late '40s carter W1's

    20190216_140055.jpg 20190216_140131.jpg
     
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  10. Rick & Jan
    Joined: Apr 9, 2008
    Posts: 422

    Rick & Jan
    Member

    This Dude used a pair of SBC block huggers and modified them just a bit to fit his Buick. He ran two pipes, just like duals, all the way to the back bumper, no mufflers. Really a different sound. IMG_2031[534].jpg IMG_2032[535].jpg IMG_2033[536].jpg IMG_2034[537].jpg IMG_2042[538].jpg
     
  11. strait8
    Joined: Jun 11, 2014
    Posts: 131

    strait8
    Member
    from Skokie, IL

    Gentlemen thank you for all the great responses and link information.
    Stooge I am wondering if the manifold you fabbed is interconnected horizontally between carbs or is each runner separate and just supported by the horizontal oval? I love the way it looks. Any reason you used single barrels over 2 barrels?
    Kbgreen I really like how that guy used the SBC headers and modified them. Seems like in the end he had to do a lot more cutting than planned but the end product looked good. Still wondering if it would be easier to get mandrel bends and start from scratch? Luckily I have a spare engine I can so all my fabrication on.
    How does one go about choosing carbs? Number, (odd, even, does it matter?))Size, jetting etc... I'd like to use my existing Strombergs . I want to improve performance as much as possible.
     
  12. Stooge
    Joined: Sep 9, 2015
    Posts: 272

    Stooge
    ALLIANCE MEMBER

    Yup, the oval tubing is the plenum connecting the 4 carburetors together, though at first, i had them on separate runners and was going to use a balancing tube to tie them together but decided on a log style intake instead. Having the tubing should also make it easier to support the throttle and choke linkages, whatever I end up doing for a fuel set up and should make it easier to have a vacuum source. I was pretty open to what I was going to use carb wise, originally I wanted to use 4 SU side draft, then was going to use Stromberg 97's mostly because I have more experience with them, but after a few months of research, studying what people had done already, and heard enough compelling cases were made by people smarter than I, to go with 4 single barrels, and should be plenty for my 320.
     
  13. carbking
    Joined: Dec 20, 2008
    Posts: 2,444

    carbking
    Member

    How about choosing carbs?

    In order of importance:

    (1) Engine displacement
    (2) Engine number of cylinders
    (3) Intake manifold design
    (4) Carburetor design (manual power system, or carbs DESIGNED to run in multiples)
    (5) Brand of carb you feel the best about modifying
    (6) Size of carbs
    (7) Type of carbs.

    EDIT: (8) after re-reading this post, adding "availability of parts" to #5 above.

    This article may (or may not) help:

    http://www.thecarburetorshop.com/Triple1barrels.htm

    Jon.
     
    Last edited: May 28, 2019
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  14. Blues4U
    Joined: Oct 1, 2015
    Posts: 3,430

    Blues4U
    Member
    from So Cal

    Now I wish I had gotten better detail pictures of this set up. Next time I get a chance to take pics of it (he's local) I'll try to do that.
    IMG_3481.JPG IMG_3482.JPG IMG_3483.JPG
     
  15. choffman41
    Joined: Oct 30, 2012
    Posts: 2,292

    choffman41
    Member

    Guys used to put 5 carbs on Jimmy sixes, just think how many you could get on a Buick straight 8.....:)
     
  16. strait8
    Joined: Jun 11, 2014
    Posts: 131

    strait8
    Member
    from Skokie, IL

    Carb king...

    (1) Engine displacement 263
    (2) Engine number of cylinders 8
    (3) Intake manifold design I like the oval log plenum style design of Stooge. I think my fab skills could pull it off But have the factory dual carb one but could sell it.
    (4) Carburetor design (manual power system, or carbs DESIGNED to run in multiples) I think manual? Dont know the difference
    (5) Brand of carb you feel the best about modifying. Not married to them but have Stromberg aauvb 267's 4 bolt style 1-2 and 1-3 on the air horn. whatever that refers to.
    (6) Size of carbs Not 100% sure. 2 barrels but do not know cfm
    (7) Type of carbs. Stromberg but again could be persuaded otherwise.
    8 I think parts are fairly available
     
  17. carbking
    Joined: Dec 20, 2008
    Posts: 2,444

    carbking
    Member

    Strait8 - call me.

    573-392-7378 (9-12, 1-4 Mon-Tues central time).

    Jon.
     

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