What Carb For My Setup?????

Discussion in 'The Mixing shop.' started by haganlee, Jul 18, 2017.

  1. haganlee

    haganlee Well-Known Member

    Hey guys, need your help. Have a 70 Buick 455 4 speed. Engine is not running great, runs ok at idle but sputtering a little when I hit the gas a bit and it is hesitating when I hit the throttle hard. Also, after it has been driven a while and I turn the key off the engine will sputter and continue to run for about 3-5 seconds. Wondering if should change carbs and if it needs timing adjusted? Trying to get as much power out of it with pretty good drivability. Below are the specs on the engine. Attached a couple of pics of the setup as well. Appreciate any help/advice.
    70 455 block bored .30 over
    Stock 73 heads
    Edelbrock Performer Intake
    Edelbrock Performer 750 carb
    Stock ram air cleaner
    TA 288-92H cam
    Stock exhaust manifolds
    3" Exhaust to 2 Spintech 3000 mufflers
    Muncie M20 4 Speed
    Chevy 10 Bolt with 3.08 Posi rear end
     

    Attached Files:

  2. techg8

    techg8 The BS GS

    You need a quadrajet calibrated for your application.
     
    SteeveeDee and MrSony like this.
  3. MrSony

    MrSony Well-Known Member

    I have a 1970 455 Quadrajet I could sell ya, but it would need rebuilt. It's a really clean carb though. It's a divorce choke model, but there are electric kits. 7040240 is the number off the carb.
     
  4. carmantx

    carmantx Never Surrender

    I agree, the edelbrock carb design is pretty generic. Will start and run or anything, but won't provide great power without some rework.
    A properly built Quadrajet will provide best fuel economy and drivability and can deliver the power when you need it.
    There are lots of other options, that can deliver power, but the good ole Qjet can be best all around.
     
  5. pbr400

    pbr400 68GS400

    You can't beat a properly running Qjet. It's like fuel injection.
    Patrick
     
  6. SteeveeDee

    SteeveeDee Orange Acres

    Time to rebuild that carb if all the eletricral is up to snuff. Two known experts who have posted here can set you right.
     
  7. DEADMANSCURVE

    DEADMANSCURVE my first word : truck

    Yep , a correct Qjet is going to be the best overall choice until you get more radical with your engine setup .
    I would first confirm that timing , compression etc is all a-ok .
    Couple things on the Edelbrock - are you running non ethanol fuel and/or additives ? Is there the recommended plate kit between carb n intake ? What is the carb part number ? 1407 = 750 manual choke , 1411 = 750 electric choke . The manual choke models have a little more of a performance setup to them . The 800 avs series might be something to try .
    If you do decide to pull the Edelbrock and redo that I can give you OEM spec parts etc info for that .
     
  8. haganlee

    haganlee Well-Known Member

    Thanks for all the help guys! I think I am going to have Mark with Quadrajet Power build me a proper QJet.
    Lee
     
  9. rkammer

    rkammer '71 GS455 Arctic White

    Addressing your run-on issue, your timing could be retarded which will cause this. Does the engine start to get hot if it idles for awhile? Also, an indication of retarded timing. Check to make sure your timing is advanced at idle at least as much as a stock motor spec. You should also power time your motor using the procedure from Larry70GS (The wizzard).
     
  10. cjeboyle

    cjeboyle Gold Level Contributor

    A wise choice. I just changed over from an Edelbrock 750 to a level 3 Quadrajet from Mark. It idles perfect, partial throttle feels like I am coasting, open the secondaries and she rips! My build is very similar to yours but with a milder cam, aluminum heads and headers. I went with a level three as I live in Florida and had no need for a choke.
    Cliff
     
  11. haganlee

    haganlee Well-Known Member

    Cliff,
    Just sent payment to Mark so I am excited to get it. I went with the level 2 and an electric choke. Just sent Mark all my specs and am going with what he suggested. Did you see a noticeable difference in power and drivability from the edelbrock?
     
  12. cjeboyle

    cjeboyle Gold Level Contributor

    I saw a very noticeable improvement over the Edelbrock. I had even fine tuned it as much as I could with bigger secondary jets. As Mark suggested I also used a 1" spacer on his carb. The part throttle driving is the most noticeable improvement. At 55 mph I have to keep lifting my foot off the throttle to be sure I am actually in the gas. The Edelbrock would start to lose power above 4000rpms while the Quadrajet pulls very hard all the way to 5000 and more I'm sure if I tried. He is usually about a month out so try and be patient, it will be worth the wait.
    Cliff
     

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