Recommended 4bbl carb for stock 318

Discussion in 'Fuel and Air Systems' started by VolksDuster, Jul 21, 2018.

  1. VolksDuster

    VolksDuster Back Yard Guy

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    I've done some searching and there seems to be a lot opinions, but they all seem to be leaning towards max power. And for the most part using newer or large older carbs but I've been trying to fine a happy medium with near stock parts.
    Before the 2bbl went back on there were long tube headers and an 850cfm double pump holley, ridiculous for what's there and what I'm looking for which brings me to now.
    So the 2BBL runs well that I put on as a temporary carb until I worked out this 4bbl idea.
    And now the only reason I'm looking to upgrade is I've also got that 4bbl intake and was wondering what would be best for my situation.
    Currently the car is a 73' Duster Twister with a stock 318 with stock exhaust manifolds and stock 2bbl intake manifold. The only changes that have been made are a dual 2.5'' dual exhaust and a high flow air filter housing, with deleted vac lines and intake heater from the exhaust manifold. I'm not entirely sure what the 4bbl intake manifold is from (340 or 360) but it has the same stampings in the same places for firing order, cylinder numbers and rotation.
    What I am looking for is low cost, better fuel economy, and extra power is always good. I'm not sure which size and model would be best, It was suggested that I use a 350cfm but said nothing else about it, another said to avoid Carter yet a third said to avoid Holley? So which is it? People say to avoid either one? My initial thought was a 450cfm Carter
    I don't know for sure, and that's why I'm looking for some help. So what I am looking for is low cost, better fuel economy, and extra power?

    Thanks
    Chad
     
  2. toolmanmike

    toolmanmike FABO Staff Staff Member FABO Gold Member

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    500-600.
     
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    • VolksDuster

      VolksDuster Back Yard Guy

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      Really? That much? I did not expect that for a stock motor. Is there a particular stock model that can be bought cheap and still be reliable?
       
    • krazykuda

      krazykuda FABO Gold Member FABO Gold Member

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      The stock dual plane intake will work fine... I prefer square bore (all 4 the same size) for street engines...


      Here's a good street model...

      Holley 4160 Aluminum Street Carburetor

      Ust this gasket to help keep the fuel from boiling....

      Edelbrock Heat Insulator Gasket
       
      Last edited: Jul 21, 2018
    • toolmanmike

      toolmanmike FABO Staff Staff Member FABO Gold Member

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      I have a 600 on my stock HP273. It runs well and I get about 20 mpg. on the highway.
       
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      • Dana67Dart

        Dana67Dart Most undignified way to get to Colorado!

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        cant go too wrong with a stock 4bbl that way you know what you have and how to fix it.
         
      • AJ/FormS

        AJ/FormS 367 FormS clone 3.09-1.92-1.40-1.09-.78od 3.55s

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        If your 318 cannot initiate a spin,on the 2bbl, then, IMO, a 4bbl is almost a waste of time and money.
        And the reason is; The secondaries may not begin to open until about 3000 rpm, and with 2.76s this is about 30 mph. I said begin to open. So at 3000, you might expect 4 hp. Count 'em . And the absolute most that 4 bbl will make, on your 73/318 is maybe 12hp@maybe 3800rpm/38mph.
        In the meantime, the bigger primaries will reduce you throttle response and probably your fuel economy too; in all but steady-state cruising..
        About the only place the 4 bbl might be a boon is when passing at 60 mph, and on the 3-2 kickdown, where the rpm might rise to about 3330. With the secondaries fully open, they might be worth 18 ftlbs or 11.4 hp.
        Like I said..... with 2.76s.
        The only thing that changes with a different rear gear is the mphs.
        Ok, but say you manage to figure out a way to fully open the secondaries without; a huge bog, stumble, or hesitation, at 2500. Lessee, that might be 12 ftlbs or 5.7 hp.............. at 27mph.
        Your results may vary.... but I doubt by much.
        On the other hand, I once put a complete 318 top end and cam, onto an early 340 short-block, and it was a real terror in a 65 Valiant wagon with just fenderwell headers, and also with 2.7s, and yes with the 2bbl.
        Ok "terror" to me, as it was waaaay too powerful for the chassis, and at age 22 it was also a handful for me, lol.
        The only difference between that 340 and your 318 then, would be 22 cubes and probably close to 3 full points of compression.

        So, IMO, for what you stated in post #1,
        get your heads shaved and bump up the compression. That will be money much better spent.
         
        Last edited: Jul 21, 2018
      • Johnny Dart

        Johnny Dart Well-Known Member

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        Edelbrock Performer intake.
        Edelbrock 600cfm carb.
         
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        • AnswerBook

          AnswerBook Well-Known Member

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          Perfect posting timing : I have a carburetor that my brother(very good mechanic) but an idiot chevy man, said was the best carburetor ever made. When I looked at him funny, he said yes best ever made. He said it was because it was so very fuel efficient and had real good horse power to boot. The best combination of the two ever made. I can not remember what he said it was, but I will find out later today. I would recommend one like this just from his response to it. It came off a 1974 Dart Sport 318. Am very curious what true mopar enthusiast thought about it. Like I said, might be exactly what you are looking for, but I don't really know.

          0921181315.jpg

          0921181316.jpg
           
        • toolmanmike

          toolmanmike FABO Staff Staff Member FABO Gold Member

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          Quadrajet replacement? Is there a number on the front of the air horn?
           
        • RPMagoo

          RPMagoo Just An Old Motorhead

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          I've had a 600, CFM, Edelbrock on 2, different, 318s, and both worked fine.
           
        • AnswerBook

          AnswerBook Well-Known Member

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          Factory replacement for the quadrajunk, if I remember correctly he said this holley was made just for mopar and said it like mopar got ONE thing over on chevy... only numbers I see is 487 on top "butterfly?" valve and 255 on bottom butterfly valve... he will be off work in a few , Ima ask him
           
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          • AnswerBook

            AnswerBook Well-Known Member

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            <Holley Economaster 450 cfm Quadrajet>
             
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            • 66fs

              66fs Well-Known Member

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              What is the part number on your intake?
               
            • AnswerBook

              AnswerBook Well-Known Member

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              wow it says 4100 340 3... it came of this intake... i did not realize it was a 340intake

              0921181505.jpg
               
            • AnswerBook

              AnswerBook Well-Known Member

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              oooo so sorry u was asking volksduster ... i shut up n go away... not my post... sorry
               
            • Ottmundr

              Ottmundr 68 Fastback

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              Do not get the summit 600cfm carb. It ices. I left a review there.

              Summit Racing® M2008 Series Carburetors SUM-M08600VS
               
            • 65Val

              65Val Average Length Member

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              Not a 340 intake...just coincidental casting number...

              4100340 1978-80 360-1978-82 318/4 Bbl Cast Iron
               
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              • AJ/FormS

                AJ/FormS 367 FormS clone 3.09-1.92-1.40-1.09-.78od 3.55s

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                I'd like to see a shot down the primaries; does it have a triple booster up front. Dang I coulda used that on my mileage testing combo; I bet that combo coulda gone better than 32 mpg. I even have a smallport intake I couldda slid under there. I was thinking maybe an old Offenhauser Dualport. Man I'd build a 360 combo just for those two items. Aluminum heads and 200psi, double overdrive and 2.94s;65mph =1270rpm,lookout!!
                 
                Last edited: Sep 21, 2018
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                • toolmanmike

                  toolmanmike FABO Staff Staff Member FABO Gold Member

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                  At the tail end of the years when American cars were big boats (1977) I worked at a Buick dealer. The ole Electra 225's and Park Avenue's with Quadrajet powered 455's would get late teens, almost 20 mpg highway. It can be done. Those old engines had more torque at idle thatmost engines have nowdays at 5000 rpm. LOL
                   
                • AJ/FormS

                  AJ/FormS 367 FormS clone 3.09-1.92-1.40-1.09-.78od 3.55s

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                  My Dad bought a nice used 64LeSabre, that I got to drive after I got my lecense, in 69. It had a 401 torque monster. I dunno what it had for a convertor but dang that was smooth. One day we were on a family outing and I got to drive! A short time after we settled into the trip, Dad leans over and says something like " are you in a hurry to get to Grandma's house?" I looked down and saw that I was speeding big time.
                   
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                  • DartGTDan

                    DartGTDan 70-71 Dart GT Fan

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                    I have an Edelbrock LD4B intake and an Edelbrock 1406, 600 c.f.m., carburetor on my completely stock (except for the MP Electronic Ignition & SummitRacing double-roller timing chain/gears) 116,000 miles 318 (auto with 3.23:1 sure-grip 8 3/4").
                     
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                    • RustyRatRod

                      RustyRatRod Just another dumbass. FABO Gold Member

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                      The 1406 Edelbrock is perfect. It's a 600 CFM carburetor, yes, but it is lean because it is tuned for economy. The 1405 is the performance version and would be a little fat. I would use the 1406 all day long, because it leaves some wiggle room if you add upgrades later on. It will work fine.
                       
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                      • RustyRatRod

                        RustyRatRod Just another dumbass. FABO Gold Member

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                        Biggest POS Holley ever made.
                         
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                        • toolmanmike

                          toolmanmike FABO Staff Staff Member FABO Gold Member

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                          And I bet it runs great and get's decent mileage.
                           
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