Chassis dyno sheet....something isn't right

General Mopar Tech Discussions

  1. justavillain

    justavillain FBBO Gold Member FBBO Gold Member

    Messages:
    63
    Likes Received:
    33
    Joined:
    Jul 17, 2016
    Location:
    Grand Rapids, MI
    Local Time:
    11:35 AM
    I was at Roadkill Nights in Pontiac MI and they had a chassis dyno. I was strapped in and made a few pulls and feel like something isn't right with this.

    A fresh build 440, 30 over, Hughes cam, forged pistons, alum heads with 84cc chambers, 1.6 ratio dbl roller rockers, msd ing, M1 single plane intake with 800cfm Holley 4150. My ignition didn't have enough on the top end it was kind of popping, and AFR was 13.5 on the top of the pull. 3.55 rear gear with sure grip. OE wheels

    So I know it needs more fuel on the secondaries but the numbers don't add up, only 250 hp to the wheels?! It torques up super hard and plants the car, and rips.

    I attached the dyno print off, and a link to some of the runs.







    E4A74494-D79F-47EF-B9AE-FBAA830A9F79.jpeg
     
  2. 1967coronet440

    1967coronet440 FBBO Gold Member FBBO Gold Member

    Messages:
    6,771
    Likes Received:
    9323
    Joined:
    Oct 26, 2016
    Location:
    Indiana
    Local Time:
    10:35 AM
    Last video sounds like there is a lot of hesitation like a fuel or ignition issue going on. Matching up with the graph about 4300 rpm it started and never recovered.
     
  3. justavillain

    justavillain FBBO Gold Member FBBO Gold Member

    Messages:
    63
    Likes Received:
    33
    Joined:
    Jul 17, 2016
    Location:
    Grand Rapids, MI
    Local Time:
    11:35 AM
    The timing is 5 degrees base with 35 total advance. Mechanical advance only.

    Fuel AFR gauge in pass side about 3" behind the collector flange. Was pretty much just 13.x the whole pass
     
  4. 1967coronet440

    1967coronet440 FBBO Gold Member FBBO Gold Member

    Messages:
    6,771
    Likes Received:
    9323
    Joined:
    Oct 26, 2016
    Location:
    Indiana
    Local Time:
    10:35 AM
    5 degree initial is way low, start playing with your timing. Typically BB Mopars like around 36-38 all in on pump fuel. Good start for initial timing would be about 15
     
    • Agree Agree x 5
    • Thanks! Thanks! x 1
    • Photon440

      Photon440 Well-Known Member

      Messages:
      8,605
      Likes Received:
      7060
      Joined:
      Mar 14, 2012
      Location:
      Surrey, B.C. Canada
      Local Time:
      8:35 AM
      Release parking brake before next dyno pull. :)
       
      • Like Like x 4
      • Bee1971

        Bee1971 Well-Known Member

        Messages:
        341
        Likes Received:
        265
        Joined:
        Jun 22, 2017
        Location:
        Sobieski
        Local Time:
        10:35 AM
        1967 I agree with you on the ignition issue above 4300 Rpms

        However

        More initial timing isn’t going to change what’s happening after 4300 Rpms when he is at 35 Total already

        5 initial , that’s 30 mechanical , so a 15 degree number T in the distributor

        Change it to 15 initial plus 30 mechanical = Not good

        Now if he had a off idle issue , yes


        Anyways


        34-36 Total Timing after 2500 Rpms is just fine

        Another degree or two isn’t going to add 200 HP


        Sounds more like a MSD ignition box problem or coil

        Did you have the Carb apart or rejet at all ?
         
        • Thanks! Thanks! x 2
        • Beach Goat

          Beach Goat Well-Known Member

          Messages:
          87
          Likes Received:
          97
          Joined:
          Aug 22, 2017
          Location:
          Virginia Beach
          Local Time:
          11:35 AM
          I typically look for 12.5-12.7 afr at WOT. 13.5 is great for cruising but not maximum horsepower.
           
          • Thanks! Thanks! x 1
          • Agree Agree x 1
          • justavillain

            justavillain FBBO Gold Member FBBO Gold Member

            Messages:
            63
            Likes Received:
            33
            Joined:
            Jul 17, 2016
            Location:
            Grand Rapids, MI
            Local Time:
            11:35 AM
            I did not jet the carb yet. I just got it all together and was fighting some odds and ends before the event.

            Proform distributor, electrical pickup (0.010 air gap between the reluctor and pickup) , msd 6AL with the rev limit set to 5500, and an Acell Super coil. No ballast resistor(bypassed by 2 10g wires twisted together and crimped together on each end to form a larger wire)

            I have a jet kit and was thinking of jumping 4 jet sizes up from what it is in it now.

            I have really pretty decent drive around after I changed the accelerator pump cam I have no real stumble.

            It has an old Holly Red pump with 1/4" nipple to 3/8 lines all the way to the pump. Now I know when you dbl the dia of a hose you actually triple the vol it can flow. But I'm not running out of fuel, because my AFR never leans out.

            Should I dial more time into it? New distributor?
             
          • 1967coronet440

            1967coronet440 FBBO Gold Member FBBO Gold Member

            Messages:
            6,771
            Likes Received:
            9323
            Joined:
            Oct 26, 2016
            Location:
            Indiana
            Local Time:
            10:35 AM
            I’m not a fan of proform parts at all, if it was me I’d be looking at replacing that dizzy.
             
          • justavillain

            justavillain FBBO Gold Member FBBO Gold Member

            Messages:
            63
            Likes Received:
            33
            Joined:
            Jul 17, 2016
            Location:
            Grand Rapids, MI
            Local Time:
            11:35 AM
            That is what was In it when I got the car so I kept it. Do you think the 35 total is ok though? I know that is what my mud truck likes with it's 350 but there is a lot of difference between an 86 square body stock motor and this 440
             
          • BSB67

            BSB67 FBBO Gold Member FBBO Gold Member

            Messages:
            704
            Likes Received:
            564
            Joined:
            Jan 18, 2018
            Location:
            PA
            Local Time:
            11:35 AM
            You're miss 100+ HP. You're problem is not in fine tuning carb jets and ignition timing
             
            • Like Like x 1
            • justavillain

              justavillain FBBO Gold Member FBBO Gold Member

              Messages:
              63
              Likes Received:
              33
              Joined:
              Jul 17, 2016
              Location:
              Grand Rapids, MI
              Local Time:
              11:35 AM
              That's part of the " something isn't right " I don't think the dyno guys where able to set it up right for my car. That is a wild dyno curve.

              The motor was just built completely, cam was degreed all new parts except the crank( oem forged) and LY rods the rest was all assembled. The car torques up hard and pulls, smokes the tires even on a roll with 3.55 gears.
               
            • BSB67

              BSB67 FBBO Gold Member FBBO Gold Member

              Messages:
              704
              Likes Received:
              564
              Joined:
              Jan 18, 2018
              Location:
              PA
              Local Time:
              11:35 AM
              Maybe its the dyno. Take it to a track. Track results don't lie.
               
              • Agree Agree x 3
              • Don Frelier

                Don Frelier FBBO Gold Member FBBO Gold Member

                Messages:
                1,268
                Likes Received:
                1282
                Joined:
                Oct 11, 2016
                Location:
                Ionia, NY
                Local Time:
                11:35 AM
                Assuming you have a MSD 6AL, just an idea but check your cylinder select loops on your ignition box.
                Perhaps the MSD thinks you have a 6 cylinder then your rev limiter would be lower than expected for example 5,500 X (6/8) = 4,125.
                Not exactly where your problem showed up but something to rule out.
                 
                • Like Like x 1
                • Thanks! Thanks! x 1
                • justavillain

                  justavillain FBBO Gold Member FBBO Gold Member

                  Messages:
                  63
                  Likes Received:
                  33
                  Joined:
                  Jul 17, 2016
                  Location:
                  Grand Rapids, MI
                  Local Time:
                  11:35 AM
                  The 2 full loops are there. That was a good idea to check it out though.

                  I have plans on switching to a different msd box and dizzy as soon as I can get the funds replenished( rebuilding 2 engines in less than 2 years takes it out of your bank acct!)
                   
                • dvw

                  dvw Well-Known Member

                  Messages:
                  4,148
                  Likes Received:
                  5504
                  Joined:
                  Feb 16, 2010
                  Location:
                  waterford mi
                  Local Time:
                  11:35 AM
                  You appear to have good torque. HP is torque x rpm / 5252. No rpm = no HP
                  Fix the higher rpm break down and you'll fix the HP number. My bet is electrical.
                  Doug
                   
                • mopar73dge

                  mopar73dge Well-Known Member

                  Messages:
                  437
                  Likes Received:
                  164
                  Joined:
                  Jan 15, 2016
                  Location:
                  Connecticut
                  Local Time:
                  11:35 AM
                  Try a diffrent coil likea FBO and the ECU they offer from 4secflat.com
                   
                • mopar73dge

                  mopar73dge Well-Known Member

                  Messages:
                  437
                  Likes Received:
                  164
                  Joined:
                  Jan 15, 2016
                  Location:
                  Connecticut
                  Local Time:
                  11:35 AM
                  Dont most dynos read as rear wheel horse power? and then it usally is only a percentage of actual engine hp
                   
                • beanhead

                  beanhead FBBO Gold Member FBBO Gold Member

                  Messages:
                  4,265
                  Likes Received:
                  6395
                  Joined:
                  May 18, 2014
                  Location:
                  Wackyfornia
                  Local Time:
                  8:35 AM
                  Proper springs correctly installed? Or possibly lifter/lash/preload if ignition doesn't fix it.
                   
                • Bb70charger500

                  Bb70charger500 Well-Known Member

                  Messages:
                  7,424
                  Likes Received:
                  6478
                  Joined:
                  May 2, 2014
                  Location:
                  fl.
                  Local Time:
                  11:35 AM
                  This is correct but at 250 to the wheels with that setup (something isn't right)
                  350-400 to wheels I'd still be trying to figure out where I'm loosing power !
                   
                1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
                  By continuing to use this site, you are consenting to our use of cookies.