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Technical 97 Carb risers

Discussion in 'Traditional Hot Rods' started by OzyRodder, Mar 18, 2014.

  1. OzyRodder
    Joined: Dec 11, 2012
    Posts: 273

    OzyRodder
    ALLIANCE MEMBER

    I have seen the thickstun Pm7 intakes and have found a picture on the forum of a 3 carb intake with what looks to be spacers/risers under the carbs.
    ImageUploadedByH.A.M.B.1395197122.262193.jpg

    I love this look but what are the potential gains/ losses by such a setup.

    Also are these spacers available or something to work on building/ideas on how to fab this. The ones on that intake almost look cast or is this a 3 carb high rise intake and I am seeing a join in the base of those risers?




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  2. OzyRodder
    Joined: Dec 11, 2012
    Posts: 273

    OzyRodder
    ALLIANCE MEMBER

    Ok. Found some reproductions available. Listed as Edmunds. Are these a "fantasy" vintage edmunds design or did he actually make these and for what benefit performance wise?




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  3. Groovybaby6
    Joined: Dec 29, 2008
    Posts: 736

    Groovybaby6
    Member
    from Denver

    Less vapor lock if the carbs are away from the heat source.
     
  4. Typically having longer "runners" will give you better low end torque. It also gives the air and fuel more time to atomize.
     
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  5. Katuna
    Joined: Feb 25, 2005
    Posts: 1,808

    Katuna
    Member
    from Clovis,Ca.

    Hey, where'd you find my pic? I don't remember posting that. Shhh, s'posed to be a secret. Hee hee.

    We're curious ourselves how it will run. It wasn't for the cool look ( even though it looks really cool). Was the suggestion of our motor builder.


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  6. Kiwi 4d
    Joined: Sep 16, 2006
    Posts: 2,486

    Kiwi 4d
    ALLIANCE MEMBER

    Will give crap low end torque ,I thought, but as gas speed rises so should power. Hi rises are designed for higher gas speeds. Triples on non progressive ( all in) a should gve a huge kick once rpm are sufficient to atomize fuel. Keep us posted.
     
  7. Two thoughts, one, it acts like a plenum to build up the air fuel charge and reduce temperature, increasing low end torque. My thought is to use an open spacer to allow both sides to mix before getting into the manifold, this would increase power. depends on how you are using it.
     
  8. tommy
    Joined: Mar 3, 2001
    Posts: 14,758

    tommy
    Member Emeritus

    I have an ad for a flathead manifold with removable risers. It said that you drive to the races and then remove the risers to race. One thing to remember is that engine performance theory has changed quite a bit from the 40s. I have 3 that came on an old Y block 3 deuce intake. They are ugly IMHO. They look like they were just added on which is exactly what happened.

    The best pair that I have are early snake oyl turbo risers with fan blades in them. They are rectangular with the 3 bolt holes. Only about 1/2" thick but I love them for the early snake oyl theory. They are the old 3 bolt 94/97 base arrangement. I see that they sell a modern version for the fuel injected cars of today. A fool and his money...
     
  9. OzyRodder
    Joined: Dec 11, 2012
    Posts: 273

    OzyRodder
    ALLIANCE MEMBER

    So how does this theory work with the Scott carb tops that place the height above the carb rather than under it as the risers do?



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  10. The 2nd-run Scott tops on my current ride provide for more air intake and an excuse for larger jets: I've thought about adding spacers on the Edmunds intake to see what it might do for low-end. Vapor-lock's never been a problem.
     
  11. OzyRodder
    Joined: Dec 11, 2012
    Posts: 273

    OzyRodder
    ALLIANCE MEMBER

    Thanks all for the input. I am considering making some wood/alum spacers to try different heights and test the effects by seat of the pants feel before dropping big dollars on shiny stuff or making my own.



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  12. Katuna
    Joined: Feb 25, 2005
    Posts: 1,808

    Katuna
    Member
    from Clovis,Ca.

    We're real curious to see how ours performs. It's set up as per our builders recommendation. As you can see, nonprogressive linkage. Can't recall if those are 4" or 5" tall.

    We're running a 4.10 gear and an aluminum flywheel so it should be interesting. I'll post the results someday when we finally finish the build.

    Sorry to hijack.


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