318 cam shaft selection/upgrade for stock engine

Small Block Mopar Engine

  1. MObarracuda

    MObarracuda Well-Known Member

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    How about this one

    Brand:Lunati

    Manufacturer's Part Number:10200701LK

    Part Type:Camshaft Kits

    Product Line:Lunati Voodoo Cam and Lifter Kits

    Summit Racing Part Number:LUN-10200701LK

    UPC:788120732703

    Cam Style:Hydraulic flat tappet

    Basic Operating RPM Range:1,000-5,500

    Intake Duration at 050 inch Lift:213

    Exhaust Duration at 050 inch Lift:220

    Duration at 050 inch Lift:213 int./220 exh.

    Advertised Intake Duration:256

    Advertised Exhaust Duration:262

    Advertised Duration:256 int./262 exh.

    Intake Valve Lift with Factory Rocker Arm Ratio:0.454 in.

    Exhaust Valve Lift with Factory Rocker Arm Ratio:0.475 in.

    Valve Lift with Factory Rocker Arm Ratio:0.454 int./0.475 exh.

    Lobe Separation (degrees):112

    https://m.summitracing.com/parts/lu...se1-_-lunati&gclid=CI3uqYritNMCFdS6wAodYaUD2A
     
  2. 273

    273 Well-Known Member

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    I'd just run stock 340 cam.
     
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    • krazykuda

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

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      I ran a stock 340 cam with Rhoades lifters in a 72 318 block with 10.5 forged pistons and 360 heads and Holley 600 vac secondary carb and got 22.5" Hg at idle and 17.75 MPG highway with 2.76 gears in a 68 Barracuda....

      I had 24" Hg at idle with stock 318 heads, but it had too much compression and would detonate, I had to lower the compression a bit with 360 heads and it was fine....
       
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      • nm9stheham

        nm9stheham Well-Known Member

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        The Lunati by RRR is getting there, and I forgot the Rhoads lifters as a good trick. Thanks KK.
         
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        • nm9stheham

          nm9stheham Well-Known Member

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          You're right on the standard cams of the day; hot rodders have not changed: MORE HP OR DIE!!! LOL But I used an HE series cam that I bought in 1974 and it worked like I described, and used it because my first performance build was in the wake of the oil embargo; I was still traveling around with 5 gallons of gas in the back 'cuz sometimes, you just could not find a station with gas. I still have the cam card.

          Actually, cams like the VooDoo are sort of the modern incarnations of that type of cam profile. The end ramps are different though. Nothing is new under the sun....
           
          Last edited: Apr 21, 2017
        • d1970

          d1970 TODAY IS A GOOD DAY TO HAVE A GOOD DAY

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          AJ, it's 211@.050 and 248 advertised, that makes it 37* from seated to .050. and it makes 16" of vacuum
           
        • nm9stheham

          nm9stheham Well-Known Member

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          That's still amazingly steep (too steep); mid-40's degrees difference between advertised and .050" duration is normal for a steep hydraulic flat tappet cam ramp. (Like the VooDoo or XE.)

          JEGS shows 221* at .050" but that has to be wrong. It is almost certain to be in the low 200's or even high 190's duration at .050" TAPPET lift, considering the 248* intake advertised duration and intake valve lift of .410". MP cam ramps are not typically the steepest around.

          Plus, if anyone measures a cam .050" VALVE lift, THAT number is going to be a lot shorter than .050" TAPPET lift. But 'at the valve' is not the standard for .050" lift numbers.
          Camshaft Choice - Camshaft Specifications - Guidelines - Hot Rod Magazine
           
        • d1970

          d1970 TODAY IS A GOOD DAY TO HAVE A GOOD DAY

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          JEGS shows 221* at .050" but that has to be wrong. It is almost certain to be in the low 200's or even high 190's duration at .050" TAPPET lift, considering the 248* intake advertised duration and intake valve lift of .410". MP cam ramps are not typically the steepest around.

          chart (3).gif
           
          Last edited: Apr 21, 2017
        • nm9stheham

          nm9stheham Well-Known Member

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          Gotcha and thanks very much; I was looking for something like that. Where is that from? The source document may explain how they measure .050" lift.

          I am willing to bet a bunch that the MP .050" numbers are a .050" valve lift, which would be at .033" tappet lift. Other similar cams are listed below for Adv duration/.050" tappet lift duration/difference:
          Crane H-248-2 248/192/56* (softer ramps)
          Lunati Voodoo 253/208/45* (fast ramps)
          Comp XE 256/212/44* (fast ramps)
          Racer Brown EH-4 250/200/50* ('kinda' fast ramps)

          Regardless, the MP is heading in the right direction for a cam for the vacuum the OP wants...'cept for the 110 LSA.
           
        • d1970

          d1970 TODAY IS A GOOD DAY TO HAVE A GOOD DAY

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        • nm9stheham

          nm9stheham Well-Known Member

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          Thanks, I never can find that site. It does not say how the .050" is measured that I can see.
           
        • RustyRatRod

          RustyRatRod Bla de blizhibliz de blatde blizi bla bla FABO Gold Member

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          Yup. That's a goodun.

           
        • RustyRatRod

          RustyRatRod Bla de blizhibliz de blatde blizi bla bla FABO Gold Member

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          It would be "ok". The reason I stopped recommending it has been covered in the posts previous to this. No one really knows what the specs "are" for that cam. In fact, I have measured more than one and gotten something different. Quality control? Proprietary grinding? Operator error? I am FAR from perfect, but since I have friends who have had similar results, I sorta think operator error ain't it.
           
        • AJ/FormS

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

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          Say Moby, what are you putting this into?
          If you are sticking to the high vacuum thinking the booster needs 18", you may be cheating yourself from some extra power.
          See, the big-cam engine may idle with a low vacuum, but you don't drive the car at idle! You can pick a cam with only a little lower idle vacuum, but pops right up as soon as the engine hits say 1800rpm,the typical stall speed. So by the time you are 1 car length out of the gate, the booster is fully charged. And if the check valve is working right, and the booster is working right, it will store plenty of vacuum, to provide plenty of assist.
          So, depending on your current cylinder pressure, you may be able to move up a bit in camming. Not much room tho with the stock compression ratio and heads.
           
          Last edited: Apr 21, 2017
        • AJ/FormS

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

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          That's what I thought :(
           
        • Ottmundr

          Ottmundr 68 Fastback

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          I have power brakes. They work. I'm running the lunati 10200701 in my 318 with a performer manifold and 600 cfm carb I am happy so far. The bad is that I have yet to install my ministarter, 302 heads, d453 headers and better gearing than 2.76. In spite of that, it's nice.

          Go here. (It should be linked to the welcome wagon forum and mandatory reading.)
          RustyRatRod's Guide To Hot Rod Bliss
           
          Last edited: Apr 21, 2017
        • nm9stheham

          nm9stheham Well-Known Member

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          That is eventually the question that was going to come up.... why 18" of vacuum? Where does that number come from? It is pretty high....
           
        • MObarracuda

          MObarracuda Well-Known Member

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          What???? That is funny you call me Moby! Good point on the vacuum at 1800 rpm
           
        • MObarracuda

          MObarracuda Well-Known Member

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          I work for Cardone (nations largest family owned auto part reman company) and had my booster rebuilt by my company. The Manager of the custom rebuild department told me the small diameter boosters need 18-20 of vacuum to work properly. My old 273 could barely muster 15-16 and the assist was marginal.
           
        • MObarracuda

          MObarracuda Well-Known Member

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          Thanks for pointing me to that link...good reading!
           
          Last edited: Apr 21, 2017
        • AJ/FormS

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

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          That is true of the dual diaphragm units.
          Not of the Larger single diaphragm 73 up units.
          And the cure for the little ones is a 15/16 M/C . When the boost goes away you will hardly notice it.
          But my 73Dart booster works just fine with a 230@050 cam that idles right around 10 ish in neutral (4speed car).
          BTW, I'm not encouraging you to buy more cam than you need; Just to entertain a bigger cam than one that idles at 18. If you are looking for performance, there are probably 2 or 3 cam sizes between stock and too-big-for-that-booster.And another 2 sizes until the bigger booster starts to go soft.
          But,if you are at stock CR,you will run out of compression first.There's just not a lot of room before the take-off gets soggy. And then you need to increase your stall-speed in compensation, and shortly after that, you will need rear gears. So, it's kindof a balancing act,between adding performance at higher rpm with a bigger cam, and loosing bottom end to get it. The only way to get the bottom back is with compression.And when that gets too high , you run outta room with insufficient octane to suppress detonation.
          Everybody is pushing and shoving,and then you run outta cubic inches and get to stroke that thing,lol,and start over.By everybody,I mean;compression,cam, octane,TC, gears, and finally, cid. And eventually you run outta head.
           
          Last edited: Apr 21, 2017
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          • nm9stheham

            nm9stheham Well-Known Member

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            OK, that is good info and makes all the sense in the world.

            One thing you might want to consider is a vacuum reservoir; it is just a family size pork 'n beans can thing with a check valve that 'stores' vacuum (i.e., stores 'nothing' LOL) and so you will always a have some high level of vacuum ready to go. It will store vacuum at the level that you had when last decelerating with the throttle closed, which, with a decently tuned carb, is easily in the low to mid 20's with a 268-ish cam. I've used one on a turbo rally car and they work fine; they just run out of 'nothing' if you pump the brakes real fast a few times.

            Of course, the vacuum reservoir won't fix low compression pistons....
             
          • YY1

            YY1 Well-Known Member

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            Rumor on the street (and this forum) is that those Summit cams are the Crane cams from years ago.....
             
          • 496 polara

            496 polara moparts id gch

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            If you are doing a cam look for a used performer intake while you have it off anyway.Very easy to overcam a 318.Lots of good suggestions already.
             
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            • Dana

              Dana FABO Vendor FABO Vendor

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              I wouldn't recommend summit brand hyd. lifters. I've got a half turn of preload on them, and they chatter like hell if the car sits for a couple days and even worse if it sits longer.
               
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