Looking for a carb recommendation

Fuel and Air Systems

  1. dodgedude

    dodgedude Well-Known Member

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    Hello,

    I have a 68 Dart, 340 .060 over 9.98:1 static compression, 422 ci. I am running W-2 heads which have been previously ported square (no flow numbers), with a matched LD340 intake, also max ported and modified to work with the W2's. The heads and intake came out of Reno, NV, where I was told Walker Evans had ran the set up on one of the desert race trucks. I believe I could use a different carb to help maximize my performance. I am currently running a Holley 750 vac secondary with a proform main body. 22 degrees initial advance, 36 total. MSD Billet distributer. Camshaft is a Hughes engines grind:

    Camshaft Technical Details

    Intake Valve Lift 1.6
    Exhaust Valve Lift 1.6 .569"
    .579"

    Intake Duration at .050"
    Exhaust Duration at .050" 237°
    242°

    Lobe Separation Angle 107º
    Intake Centerline 104º
    Intake Opening at .050"
    Exhaust Opening at .050" 14.5° BTC
    51° BBC

    Intake Closing at .050"
    Exhaust Closing at .050" 42.5° ABC
    11° ATC

    Min. Suggested Cylinder PSI 160

    RPM 1800-6200

    I am running 1.6 rockers.

    What carb would you suggest? 90% street use, summer only, with a weekend or two at the strip. I am at 6000 feet elevation, which I know doesn't help.

    Thanks in advance!
     
  2. jdsduster

    jdsduster Well-Known Member

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    i would think the one you have now,what is wrong with it?or are you just wanting something new or differant?
     
  3. EL5DEMON340

    EL5DEMON340 Well-Known Member

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    Holley 950 HP, maybe a 800 or 850 dp
     
  4. dodgedude

    dodgedude Well-Known Member

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    The one I am running has issues, throttle blades and shafts worn, etc. Looking to see if anyone has experience with the Quick Fuel series for street use, if so, which one? Or should I stick with a regular Holley? I do not want an edelbrock or carter style.
     
  5. hollywood hig

    hollywood hig King of the assklowns

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    i would think a 850 w/the cam u have..........i'm in denver and run a 750 holly vac. sec. also. but my cam is not as big..........it runs pretty good here.

    guess you'll have to experiment...........pull the plugs and see what they look like.....
    higgs
     
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    • crackedback

      crackedback FABO Gold Member FABO Gold Member

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      It's a 422 inch engine? You have 340 at .060 then say 422...

      I'd get a 950hp style carb that has a LOT of adjustable features. Air bleeds, IFR, emulsions.
       
    • dodgedude

      dodgedude Well-Known Member

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      Yes. 422. 4.100 bore. 4" stroke. Plan to twist no higher than 6200.
       
    • Woods74

      Woods74 Broke Senior

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      Quickfuel.
       
    • jimjimjimmy

      jimjimjimmy lobsterman FABO Gold Member

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      x2 950hp .
       
    • RustyRatRod

      RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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      I would say at LEAST a 950 HP, maybe even a Dominator. My GAWD what you have on it now may as well be a 2 barrel.

      Also, FWIW, I would seriously consider going to a much stouter camshaft....a big solid roller. That coupled with the bigger carburetor will wake it up. Right now it's unconscious.
       
    • flyfish

      flyfish C8H18+N2O = :-D

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      If the carb is worn out and you are going to replace it anyway then I would go with a 950 Holley dp for max power potential....but for what you do with the car, your current carb would be fine.

      FWIW, my car has a small street roller (.576/.582 lift) and a Holley 650dp that I transformed to a 750dp with a Proform main body and its not hurting for power (see times below). Those Proform main bodies flow REALLY well compared to the stock piece with the choke horn.

      Power depends greatly on the parts combination, and tuning skills. JMO.
       
    • clinteg

      clinteg Well-Known Member

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      Have a Holley 950HP on a setup similar to yours and the car is mostly street driven. With the old camshaft and ignition, the carb was great. With the bigger roller cam and new ignition system, I can't get it to idle worth a crap when in gear. My engine guy couldn't get it to idle well either. He thinks it's something to do with the distributor and the timing going out of whack due to the lope, but who knows. I know that it was really nice with the old setup but it's struggling with this setup to idle. Other than that, it's been a good carb.
       
    • cuda66273

      cuda66273 Well-Known Member

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      CFM Required 757.0601851851852 100% VE
      CFM Required 696.4953703703703 User 90% VE

      You may have a great set of heads but to utilize their full air flow potential you need more cam, more compression and a lot more RPM

      Rounded off and all things considered we would use a Q-750 Mechanical to give you decent drive-ability on the street. This is assuming you have the correct convertor or a 4 speed and a good rear gear ratio.

      22/36 Ignition timing? Are you using one of our 14* bushings in the MSD distributor?

      You will need to consult with a Quick-Fuel expert and get the Idle Air Bleeds adjusted at the factory or at least supplied. The generic air bleeds are not matched to your cam and compression.

      Email me if you'd like a price quote.
       
    • roccodart440

      roccodart440 Well-Known Member

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      Quickfuel or holley HP series. I have a quick fuel running on my father street rod and it works great on the street. Go with a mechanical secondary carb.

      I'd go 850cfm but I'm sure it will run with the 950 and have a bit better max effort. I'm running a 950 with more cubes, more cam, more compression, more heads and I don't care to go bigger. Mine runs well and the AF chart is spot on. The slightly smaller carb will most likely be slightly more fun for you on the street and yield slightly less performance at the strip.
       
    • crackedback

      crackedback FABO Gold Member FABO Gold Member

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      The 950hp with a 1 3/8 venturi DOES NOT flow 950cfm. More in the area of 820ish. Marketing at it's best.
       
    • roccodart440

      roccodart440 Well-Known Member

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      How does that compare to a proform 950?
       
    • dodgedude

      dodgedude Well-Known Member

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      Yes, I would like to visit with you concerning the carbs available. Please contact me at 620-282-7337.

      Thanks,

      Clark
       
    • stroked340

      stroked340 FABO Gold Member FABO Gold Member

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      Quickfuel 850....
       
    • 70aarcuda

      70aarcuda Master Hoader of SBM FABO Gold Member

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      Look at the venturi size...if it is 1 3/8 then it flow 830 ish...as said above...marketing twice..

      found this


      Holley 750 HP...1.375 X 1.720
      Proform 750.....1.375 X 1.720
      Holley 950 HP...1.375 X 1.750
      Proform 850.....1.400 X 1.750
      Proform 950.....1.450 X 1.750
       
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      • roccodart440

        roccodart440 Well-Known Member

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        So what does this mean it flows at? 1 3/8 you say is 830cfm so 1.450 would be? I'd hope 950?
         
      • crackedback

        crackedback FABO Gold Member FABO Gold Member

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        4 barrel carbs and most calculators are rated and set up using 1.5" manifold vacuum.

        I don't know a single engine builder that builds an unrestricted engine to pull 1.5" at WOT for best power.

        Most numbers you calculate, dropping the manifold vacuum to .75", will multiply the cfm requirements by 1.414.

        I use those calculator to identify the smallest carb I'd consider using.
         
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