Highest LIft cam with 68 340 with stock intake and carb

Small Block Mopar Engine

  1. krazykuda

    krazykuda Well-Known Member FABO Gold Member How-To Section Editor

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    I have some W-2 heads up for sale if you need them...
     
  2. AJ/FormS

    AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s

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    Here's what I mean; the specs on that cam are 273/276/110/106 and 56* overlap.
    >plugging the numbers into the Wallace calculator, assuming a true Scr of 10.8, this nets a Dcr of 8.7@178psi and a VP of144. That's a nice safe place to be. With the aluminum heads and tightQ you could run 87E10 with the right tune.
    >Now suppose we swap in the popular 268/276/110/106/and 52* overlap. The logs will still choke the overlap cycle, but now, still with a 10.8Scr, the Dcr rises to 8.86@182psi and the VP to 151. I have run 8.86 on 87E10, so I think this is still fair game as to Dcr.
    >Now suppose we dropped another cam size and reduced the LSA to 106 for the 4 speed. Still with 10.8, the Dcr now rises to 9.0@187psi and the VP to 158! And the overlap dropped to 52*. I have run over 187psi on 87E10, so we're still on pumpgas. Of course the logs are still choking the overlap.
    So in each of these cases, as to lower rpm torque production, less is more. and because of the choke, very little top-end power will be lost. Also with each size smaller cam, the power extraction period gets longer, and that usually means better fuel economy at part throttle.Also each smaller size cam is bring the power peak down to a more useable rpm, making the midrange a happier place to be.
    Now, on all of them, the choked overlap is choking the power production upstairs say beginning around 4000 and reducing the power little by little-more from there to your shift rpm.

    In my previous combo;a 367 4 speed, I was running 10.9/8.9/@184psi and a VP of 162, and I can assure you that at a VP of 158 will have a tremendous bottom-end.I think it must be 7000 ft lbs or more,lol; that's an exaggeration ok.

    Ok but the cam is staying, so then we run with the choked overlap. So like you, I'm wondering how much power is being lost? IDK. And does it really matter to you? Probably not , cuz you're a streeter with a 10.40 starter gear. And the combo spins to at least, I'm guessing,50 mph AS IS. So roughly 85% of the time, you already have more power than the chassis can handle! lol.
    So that's why I say; make it hook first. Then headers. Then you can fool around with intakes and such.
    But if you really want to install a different intake and carb, go ahead. But it will just spin the tires exactly the same as it does now, and you will not go one mile an hour faster from zero to 60 lol, nor one second quicker; not until it hooks and not up to it's true potential, until the headers go on. It's kindof like putting your socks on after your feet are already in your shoes. Namely certain things have to be done in a certain order.
    Anyways that's my 2 cents worth.
    BTW; nice cam. I'd make that one earn it's keep. If I had it in my 367, the AG and 750DP would finally come alive: 243@ .050 is sweet, just not with a FTH of 292/108 lol.
     
    Last edited: Aug 3, 2017
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    • flyfish

      flyfish C8H18+N2O = :-D

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      Sorry, that was meant to be 1/2 joking considering you never mentioned your heads...and since there was almost no detail in the post I just took a stab in the dark that you probably had stock heads and a big-ole cam.

      I really have no idea what the original post meant "With stock intake and carb, What is the highest LIFT cam you can get away with?"....Its kinda like asking.....With a 500hp motor, if I turn left what kinda of syrup goes on my pancakes.....

      I'm not trying to be a poop, I just don't understand your question.
       
    • 1968FormulaS340

      1968FormulaS340 Well-Known Member

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      The Victor 340, Holley 800 coupled with Drag Radials and Headers, will make the car brutally fast.

      Right now the car can destroy the E70-14s. If you put the Victor 340 and Holley 800 on, it will still destroy the E70-14s.

      That's the information provided above, in a nutshell.

      And that was my theory when I installed that cam (its actually less aggressive than the Crower solid roller it replaced). I wanted the car to be fast with the stock parts while having an easy path to making it very fast again. With the Crower cam, headers and slicks the car ran a best of 11.78, @ 118 mph.

      As the car sat, when I sold it, running on the E70-14s I ran a best of 13.2 at 105 mph, if I am remembering correctly. The car is extremely difficult to launch on the E70-14s. My times on the one day I had it at the track ranged from high 15s to that 13.2
       
      Last edited: Aug 3, 2017
    • yellow rose

      yellow rose Overnight Sensation FABO Gold Member

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      Oh crap...it's your car. Now I get it. Makes sense now.

      OP, take that thing out and beat on it.

      BTW...at 118 MPH that thing could have gone 11.20-11.30. It's a runner.
       
    • IQ52

      IQ52 Well-Known Member

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      Tell us more about the heads, other than they have 2.02 intake valves.
       
    • 1968FormulaS340

      1968FormulaS340 Well-Known Member

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      They are the Original X heads that have some work done on them. The work was done professionally but was done while the previous owner had it so I can't give specifics.

      Harland Sharp rockers.
       
      Last edited: Aug 3, 2017
    • yellow rose

      yellow rose Overnight Sensation FABO Gold Member

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      I tried to get my brother to drive out and buy that thing when it was for sale.
       
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      • johnnycuda

        johnnycuda JohnnyCuda's 68

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        huh???
         
      • yellow rose

        yellow rose Overnight Sensation FABO Gold Member

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        Now you did it.

        AJ will reply with a tome of biblical proportions. If I may be so bold...I *THINK* I
        He is saying you log jam is the exhaust manifolds.

        I didn't read it all...but that's what I took from it.
         
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        • moper

          moper Well-Known Member

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          Assuming "no" meant it's still a 340. I wouldn't put a Victor on a 340 unless it was in a very light full race car. If you also have factory HP exhaust manifolds then you're leaving a bunch on the table and a Victor is the wrong add-on. Headers, an RPM, and a decent carb and you're there.
           
        • yellow rose

          yellow rose Overnight Sensation FABO Gold Member

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          And headers.
           
        • 273

          273 Well-Known Member

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          I'd say headers 1st on a cam with decent amount overlap needs a good flowing exhaust over intake carb. If exhaust is free to leave your engine it will help pull air in even throught a restrictive carb intake. But with poor exhaust hard to get good air flow if the exhaust is trying to get out the way it came in (intake). Seems to me your engine needs headers, airgap and 750 Holley or smaller cam.
           
        • lilcuda

          lilcuda Well-Known Member

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          I assume that this thread means you decided to keep the car?
           
        • johnnycuda

          johnnycuda JohnnyCuda's 68

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          I can still use the money more than the car so if it sells it sells mean while i can't help but play
           
        • moper

          moper Well-Known Member

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          That's why headers was first. It will take a custom cam to do much with stock exhaust manifolds, and you'll still be leaving power on the table. A friend's Stock Eliminator 351C ford mde 485hp with unported heads, stock 9:1 static, stock iron intake, and stock autolite carb. But it had big dollar stepped equal-length headers and a custom hydraulic cam with stock lift to work with it all.
           
        • 1968FormulaS340

          1968FormulaS340 Well-Known Member

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          He doesn't "need" to do anything unless he wants it faster. It's already a low 13, high 12 car.

          But yes, headers would be the first step in making it faster.

          Next, would be the Victor 340 and Holley 800, because he already owns those and they will work fine.
           
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