Carb replacement for 1969 430 block

Discussion in 'The Mixing shop.' started by srb, Jun 14, 2017.

  1. srb

    srb Well-Known Member

    Hi guys,

    I own a 1969 Buick GS 400 with a 430 engine in it. I believe it is a Riviera's, but I'm not sure.
    The engine was honed some years ago to a 438 CUI and is completely stock. Currently I'm restoring my car and I also want to do some minor things to my engine. I've purchased an HEI ignition and I want to replace my carb.
    Currently there is a 4160 600 CFM Holley installed, but I understand a Rochester quadrajet is the stock carburator. And from what I understand from this forum is that it is good carb. But I have a few questions.

    -First off, I see a Riviera carb (7029241) and a non-Riviera carb (7029240). What is the difference? Does it apply for me?
    -If I'm correct, this carb is a 750 CFM one. Even though it is stock, isn't that too big? When I use a CFM calculator 600 CFM, what I have now, sounds about right. (5500 rpm)
    - Is it really a good carb?
     
  2. techg8

    techg8 The BS GS

    A quadrajet will do you fine.

    There is no appreciable difference between the -241 and the -240, either would be fine for your application, especially if tuned by a competent builder.

    750cfm is the maximum cfm referred to for the casting of that era. Quadrajets were used on a wide variety of engines from small v6s to large v8s, all with "750cfm" carbs. The cfm capability was limited via a mechanical stop on the secondary air flaps, and the carb was tuned accordingly for the application.

    Bottom line, don't worry about the 750cfm designation and cfm calculator stuff. In stock form either of those carbs will work for you. For best results have it rebuilt/tuned by a competent builder who will set it up for modern fuel and have it running like new.
     
  3. telriv

    telriv Well-Known Member

    You could also have Ken set you up with a later 800CFM Q-Jet set to your specs. The nice thing about the 800 is it's more modern. Ken could explain far better than I could.
    What's you say Ken???
     
  4. srb

    srb Well-Known Member

    Thank you for your reply. I probably still need a few months before I can proceed with the engine, but I'll be looking for a Q-jet then.
    Hopefully I can find a proper one here in Holland.
    The tuning part, is that turning some screws, or do special items need to be installed? What I'm actually asking is, can I just buy any -241 / -240 carb and tune it myself with a gas tester?
     
    Last edited: Jun 15, 2017
  5. techg8

    techg8 The BS GS

    7029240 or 7029241, yes you can tune it with rods and jets if needed.

    Be aware that a quality rebuild is important. "Throwing a kit" into a quadrajet usually doesn't cut it. Lots of info online about it.
     
  6. carmantx

    carmantx Never Surrender

    If you get a properly built 240 or 241 carb from Ken or I, or any other reputable builder, you can fine tune externally.
     
  7. 436'd Skylark

    436'd Skylark Sweet Fancy Moses!!!!!

    i have a 430 carb core i can sell for a good price. let me know if your interested
     
  8. lemmy-67

    lemmy-67 Gold Level Contributor

    The last 3 digits of the carburetor part number (240 vs 241) usually has to do with engine displacement, manual vs. auto transmission, and the presence of emissions hardware. The electra/wildcat/riviera all used the same engine and transmission, but the weights and final drive ratios can vary....so there may be some minor differences in the carbs.
     
  9. srb

    srb Well-Known Member

    Ok thanks for your information guys. I'll finish the bodywork first, but after that I'll be on the lookout for one.
     

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