Where to degree this cam ?

Discussion in 'Small Block Mopar Engine' started by mbaird, May 28, 2018.

  1. mbaird

    mbaird mbaird FABO Gold Member

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    5.9 Magnum
    9.4ish compression
    Dougs headers
    IMM EQ heads
    Air gap intake
    2500 stall
    3.55s
    68 fastback
    Street driver with a few track days here and there.

    Where would you install this cam and why ?



    20180521_151457.jpg
     
  2. skrews

    skrews Well-Known Member

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    108
     
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    • yellow rose

      yellow rose Doctor of Thinkology.

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      What did Kenny say. He usually tells you where to centerline it. I'd think 108 is pretty close.
       
    • mbaird

      mbaird mbaird FABO Gold Member

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      He didnt say... I assumed it would be on cam card. I can call and ask him tomorrow.
       
    • mbaird

      mbaird mbaird FABO Gold Member

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      I was curious about the different responses and reasons behind them .
       
    • OLDSTYLE

      OLDSTYLE Well-Known Member

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      says 108 on the card
       
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      • mbaird

        mbaird mbaird FABO Gold Member

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        Are you saying ICL is always where cams are installed ?
        Or did I miss something on the card ?
         
      • Marcohotrod

        Marcohotrod Well-Known Member

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        Line up the dots, degree it. If it is 106 or 107 or 108, run it. Advanced = more low end, later = more top end. It is up to u
         
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        • iScamp

          iScamp Well-Known Member

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          I really don't know much about setting up performance engines. My current setup is definitely not ideal. Yours seems to be properly tuned. Anyway, my too big of a cam, low compression 318 has a .484 lift, 284 duration cam that was degreed at 108, per the cam card. I had poor acceleration and throttle response. Mind you, my torque converter was already pushing my vehicle way before the optimum range of the cam. Catalog says 2600-6000 rpm. I advanced the cam 4 degrees (set it up on the triangle). Much better throttle response and low end torque. Don't know if that little tidbit is even relevant to what you are doing but, you said yours was for the street and occasional track.
           
        • 69conv

          69conv leaky gasket FABO Gold Member

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          Did you do anything to the heads?
           
        • mbaird

          mbaird mbaird FABO Gold Member

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          Heads are Brians EQs with 2.02/1.60s , bowl work , a good valve job , guides cut for more lift and better springs.
          Supposed to flow over 260 @ .550
          The point of the thread is to discuss the WHYs of various install opinions. I cant say I am an expert and would like to learn more.
           
        • AJ/FormS

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

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          I get it; the cam is already bought, and the engine is already built; So then, I'm with marco; dot to dot, and what will be will be.Once you wind her up, she'll rip chit reasonably well. And if it's too soft for you, just throw more TC at it.
          _______________________________________
          IMO, in a streeter, I wouldn't put that cam in there at all, unless you chose it for a specific reason, ie the idle lope.
          IMO it's the wrong cam for that combo.... until around 3500 and beyond. Why? Because the bottom end, at 9.4Scr, is gonna be soft. If you install it at split overlap/110, then the ICA will be 67*, and at 9.4Scr, your Dcr will be down at 7.38. Your cylinder pressure will be around 139psi@115VP@1000ft elevation.
          How soft is that? That's about what an 8.0 Scr teener makes. So from stall to 3000/3600 it will feel like a low-compression teener. Well,with the 2500TC, it will feel a bit stronger, like an 8.0 teener with a 2500TC,lol.. With 3.55s; this is about 27 to 32mph.
          But why is this? because that cam has ultra slow ramps, taking 52* to go from .006 to .050 and back, which makes for a very late closing intake. That's just how hydraulic rollers are.
          If you install it at say 106, then the numbers are 9.4/7.59/144psi@123VP@1000 ft. Ok, 123VP is like an LA 318 at 8.5 Scr, So it's better but.............. as you can see it's only 5psi. However; those 5psi translate to 7% more VP.
          More VP is a good thing until you get to about 140/145 in an A-body. After that it's just a tire-fryer.And; VP is only important below about 3000 rpm.
          The problem with putting the cam in at 106 is that to get the extra 4* of compression we stole it from the power stroke, so now that is 4 degrees shorter ending at 101, which means some pressure is going out the pipes instead of being applied to the crank. What does that mean. Well, you paid good money to make that pressure, and now 4 more degrees of it are going straight out the pipes, decreasing your fuel efficiency, and you can't do a dang thing about it.
          Your application wants a tighter LSa and your engine wants an earlier closing intake.And a streeter wants more degrees dedicated to compression plus power.So if it was me I'd just put a cam like that, in there, in the first place.

          This cam, in at 110(split overlap) wants 10.5 Scr to get a Dcr of 8.2 and 160psi@ a nice 133VP, at 1000 ft .
          With a tight-Q and closed chambers, you could push 165psi; and at 1000ft that would change the numbers to 10.7/8.37/164psi@136VP....... now you're getting somewhere. 136 would work with 2500TC and the 3.55s..

          But I get it; the cam is already bought, and the engine is already built; So then, I'm with marco; dot to dot, and what will be will be.Once you wind her up, she'll rip chit reasonably well. And if it's too soft for you, just throw more TC at it.
          With 3.55s; 65 is about 2870, so I'd go with a 2800. Now you are close to not caring about VP
           
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          • RustyRatRod

            RustyRatRod Just another dumbass. FABO Gold Member

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            If your static compression ratio is REALLY a TRUE 9.4:1, I would run that cam straight up.......but degree it to make sure it's there.

            .050" duration is small, it will build cylinder pressure on an engine with already fairly high compression......9.4 + small duration @ .050 plus an advanced camshaft position on top of that could cause some detonation issues on pump gas.
             
          • nm9stheham

            nm9stheham Well-Known Member

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            With you altitude being 2800' and higher, and being mostly street, I'd advance it to around 106-104 ICL, to get a bit more low end torque, like noted in post #9. But I tend to go more for low RPM torque than some others.

            I'm not really seeing any loss of power being significant for being early on the exhaust opening as AJ discusses above. (Good detail BTW). Your good head breathing is going to do a lot for the mid and high RPM power. And I'll disagree on the loss of fuel efficiency discussed there.... you lose more fuel efficiency going to a longer overlap with a tighter LSA than you do by opening the exhaust early and losing a small amount of the already low cylinder pressure at the end of the power stroke.

            Interesting to see the cam duration specs down to .002" lift.... I don't recall ever seeing that low lift spec before.

            It is also interesting to see the checking tappet diameter being .812"....! I am thinking that will make the durations measure shorter but I am not 100% sure.
             
          • mbaird

            mbaird mbaird FABO Gold Member

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            Yeah the .002 caught me offgaurd. I am not sure those lower numbers are correct.. maybe a typo. Seem kinda high.
             
          • MOPAROFFICIAL

            MOPAROFFICIAL Well-Known Member

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            Set the intake closing @39 ABDC , re check it 3 times.... then button it up.

            You don't need to advance it, if you did... I wouldn't bother with anything less than 4 degrees advanced.
             
          • nm9stheham

            nm9stheham Well-Known Member

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            It just may be old school type of numbers they have been doing forever at Oregon, or a way to check their work in regrinds. Regardless, I just found it interesting.
             
          • 72Dart6pack

            72Dart6pack Harder Better Faster Stronger.

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            112° sounds like good place. :)
             
          • MOPAROFFICIAL

            MOPAROFFICIAL Well-Known Member

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            The why would be ..if it's the right cam, you shouldn't need to install it any other way than where the grinder says to.
             
          • Wyrmrider

            Wyrmrider Well-Known Member

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            what is it a copy of?
            274@.006 will be as AJ said- soft
            I'd start with the 108 the grinder recommended
             
          • mbaird

            mbaird mbaird FABO Gold Member

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            Here is where it came out after jacking with it for the better part of a day. Weird thing is I had to use the 8A mark on the Cloyes timing set to finally get in the ballpark. And I have a small descrepency between camsheet and actualls....this could be that smaller lifter he used ????

            Circled number are my final measurements.
            I triple checked everything....
            20180611_125304.jpg
             
          • nm9stheham

            nm9stheham Well-Known Member

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            IMHO the cam was ground keyed off that 8 degrees. And the intake was ground a little early. So the LSA closed up a bit.

            For a flat tappet....a lifter diameter change will change lift angles equally and in opposite directions on both ramps of each lobe, so should not change the ICL and ECL or LSA or the install angle on the spockets. But I missed earlier that this is a roller; the comment on the diameter was for thinking it was a flat tappet.
             
          • mbaird

            mbaird mbaird FABO Gold Member

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            What is the reference to "1 1/2 degrees overlap @ .050" mean ? Any idea ?

            I will call and talk to him today.
             
          • nm9stheham

            nm9stheham Well-Known Member

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            I can't answer that... from the specs, it looks like 5 degrees overlap at .050"..??? I'd like to hear what you find out.
             
          • mbaird

            mbaird mbaird FABO Gold Member

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            He is out of town till next week.

            AND THIS IS WHY WE DEGREE CAMS FOLKS !
             
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