Please Help Me Decipher My Cam Specs Sheet

Discussion in 'Small Block Mopar Engine' started by MobileCustoms, Oct 15, 2018.

  1. MobileCustoms

    MobileCustoms Well-Known Member

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    This is the only spec sheet I got for the Erson hydraulic roller cam in my stroker build. Just would like to know which numbers are the most important ones when I am being asked for my cam specs. I am ready to have a torque converter built but feeling a little dumb when I look at this sheet. LOL
    Thanks to anyone who can dumb it down a bit for me!

    Cam Specs.jpg
     
  2. Willyrd

    Willyrd Well-Known Member

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    Peak Valve Lift, so .547, Lobe separation angle so 110, and duration so 285/279
     
  3. BigBlockMopar

    BigBlockMopar BigBlockMember

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    Duration 279°/285° at .050" valve lift.

    (The top table relates to the Exhaust lobe specs, the bottom table are the intake specs.)
     
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    • MobileCustoms

      MobileCustoms Well-Known Member

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      Thanks guys! what tells you which table is for intake and which is for exhaust? Is it top dead center VS bottom???
       
    • Willyrd

      Willyrd Well-Known Member

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      Im guessing E1 is exhaust and I1 is intake
       
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      • MobileCustoms

        MobileCustoms Well-Known Member

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        Ahhh... simple enough. Thanks!
         
      • Bad Sport

        Bad Sport HALF A BUBBLE OFF Staff Member FABO Gold Member

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        Just send that cam card when you order your converter. :D
         
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        • 360duster

          360duster Well-Known Member

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          isn´t it 254/249 @.050"?

          Michael
           
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          • MobileCustoms

            MobileCustoms Well-Known Member

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            I see what you're saying.... ?
             
          • MobileCustoms

            MobileCustoms Well-Known Member

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            Yes, but I still wanna know the simple numbers for myself and when others ask! PTC doesn't have an option in their online form to upload or attach anything, they just want the meat and potato specs
             
          • dart19666

            dart19666 FABO Gold Member FABO Gold Member

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            Since I use these for a living here at Crower that is 249/254 duration at 0.050" on a 110LSA lobe lift of 0.365"/0.364" then just multiply that by the rocker ratio to get valve lift. Now that is the obvious stuff but here is the not so obvious info. Look at the left hand side that shows the "Open,nose close ACC" "Acc = Acceleration" that is the second derivative and this info looks not so good. This cam will be prone to noisy lifters and valve float. Notice the open Acc is slower than the closing? well this means that spring set up will be imperative if not critical when going over the nose at anything over 5,000rpm to keep the lifter from slamming down on the cam. I personally would have used different masters than these. This is just my two cents. Ask if you have questions.
             
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            • nm9stheham

              nm9stheham Well-Known Member

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              It's....

              249/255 duration @ .050" (Intake is normally listed before exhaust.)
              307/314 advertised duration
              LSA: 110 (as noted)
              Tappet lift: .365"
              Valve lift with 1.5 rockers: .547" (as noted)
              ICL: 110 (or so it is listed...)

              ICL is 'as ground' and installed dot-to-dot, if everything is machined right. (But you can install it at a different ICL to move the torque curve around....Does PTC ask for an ICL input?)

              Nice to have all of that data IMHO... but, agreed, few people would ever use it.
               
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              • nm9stheham

                nm9stheham Well-Known Member

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                I saw those numbers and was very intrigued.... But, if you don't mind my asking, isn't the absolute value of the 'over the nose' acceleration the most important one in determining the spring requirements and keeping the lifter on the lobe? Once the acceleration has gone + again on the closing ramp, then the lifter is already in contact with the lobe...

                Do you happen to know the units of acceleration used on this card? Just not clear to me....
                 
              • MobileCustoms

                MobileCustoms Well-Known Member

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                Interesting... Well, here's the dyno sheet off the last pull. It didn't want to go much over 5800 rpm
                Edit to add info: I have solid lifters. with 1.5 ratio comp roller rockers

                Dyno Pull # 10.jpg
                 
              • dart19666

                dart19666 FABO Gold Member FABO Gold Member

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                cam-dent.jpg

                If the ramp is to steep without enough spring pressure to keep contact with ramp at a high rpm, they will free fall. Also Hydraulic lifters are much heavier that solid lifters so these numbers are much more critical. Here is a pic of a gen III hemi cam that had the same problem. I had to angle the pic so you can see.
                 
                Last edited: Oct 15, 2018
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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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                  The events are listed in the two columns titled close and open. FRom the .006 events all other relevant specs can be calculated. that thing is huge, and 90* overlap! 90 flipping degrees, I think I ........ mighta maybe ......almost ........hadda accident.
                  Boy I bet that's gonna be a fun tune.
                   
                  Last edited: Oct 15, 2018
                • AJ/FormS

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

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                  I don't know much about dyno sheets , but one thing I know;
                  14s AFR at 5800WOT is not good.
                   
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                  • MobileCustoms

                    MobileCustoms Well-Known Member

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                    so then... which numbers should I actually use when being asked for my cam specs? Looks like a good shift point is right around 5400 rpm, correct?
                     
                  • MobileCustoms

                    MobileCustoms Well-Known Member

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                    I do plan to run a FiTech system on the car.
                     
                  • AJ/FormS

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

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                    Chebbys do that all the time right?
                    The varnish in the dip is the giveaway,lol.
                     
                  • dart19666

                    dart19666 FABO Gold Member FABO Gold Member

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                    That would be a gen III hemi cam. Not enough spring pressure on a lobe that has way too much Acceleration on the closing ramp. I fix these cam specs everyday. This will happen and does happen alot, when proper care is not taken when picking lobe masters.
                     
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                    • stixx

                      stixx FABO Gold Member FABO Gold Member

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                      We don't know the rest of your engine except that it's a stroker (cylinder heads would be most interesting), but a stroker with that much cam
                      nosing over at only 5400RPM is not a good thing in my book. Unless you are running stock-ish heads. My 2 cents.
                       
                    • MobileCustoms

                      MobileCustoms Well-Known Member

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                      Well you are correct, that for now at least, the engine had mildly ported J heads/2.02 valves. So yes, it is very much head-limited. I appreciate the input from everyone.
                       
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                      • nm9stheham

                        nm9stheham Well-Known Member

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                        Yes, I understood what you are saying. The pix is very good. I am still working through whether it is the peak closing rate, or the peak rate over the nose, that matters.

                        The closing acceleration rate being + means it is applying force to the valvetrain in the opening direction, correct? (Which is not really 'opening' at that point in time, but is stopping the closing action; i.e. bring the valve train to a stop.)

                        If you pick a lower peak closing rate, does the over-the-nose rate also typical go lower? (Does not seem likely to me...)
                         
                        Last edited: Oct 16, 2018
                      • nm9stheham

                        nm9stheham Well-Known Member

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                        Forget the acceleration rates for the TC selection; that is a different matter entirely, and is a side discussion to what you want. Use what was summarized in post #12.

                        As for the best shift point, it depends more on how the torque drops off below the data presented in your dyno sheet. If the RPM's dropped from 5400 to 3200 RPM on a 1-2 shift for a 904, then what is the torque at 3200? Can't tell from the data... IMHO, for drag racing, you would upshift at the point where the after-shift torque is roughly equal to the pre-shift torque... i.e, you evenly 'straddle' the torque peak before and after the shift. (And I can see it varying from there but that's 'in the ballpark'.)
                         
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