Taking edge/acceleration off a motor?

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  • driver99
    Senior Member
    • Aug 2007
    • 106

    #1

    Taking edge/acceleration off a motor?

    All of this is for a dirt circle track open wheel modified so keep that in mind. I work with a driver who is having problems setting up the car and driving it with a new motor combo. He can not get the initial traction he needs on throttle up and once he loses the grip the motor seems to be not forgiving enough and he never gains the traction back. Now when he does get the initial traction the motor is fantastic but the error room for him/car is just too small compared to what he is use to. His old motor he could just hold it wide open coming off and just not worry about it, unfortunately that motor blew up and this motor is the only option. What we need to do is find a way to try and keep the top end power but take some of the edge off as it is throttled up mid corner. What are some of your thoughts on taking the response/torque out of a motor at lower corner speeds? For reference his old motor ran the same cam as this one but was a 360 done 4.125 bore and short stroke with a lower rise manifold. Current motor specs:
    Alcohol, 360 CI chevy, 4.030 bore, 3.562 stroke, 6"rod, 44Ib light weight crank (old motor combo ran standard weight), 13.5 compression, World Products Sportsman 2 heads Stock with only slight bowl work, 2925 edelbrock intake with extensive work, Willys 750 slick track carb, bert transmission, cam is Bullet 256/264 @.050 .430 lobe lift 107 separation installed on 105 Intake center, 1.6 ratio shaft rockers on both intake and exhaust, .016 Intake .018 exhaust lash, Tri-Y headers. Now keep in mind driver and car owner will NOT switch away from alcohol and I'm not sure they will go for a cam swap, but anything else is a possibility.
    My thoughts: ditch tri-y's and see if normal style long tubes will kill off some of the throttle response? Or open lash up into the .020's? I'm just at a loss, driver hates this motor says its just too much and blames it all on the lighter crank and bore combo versus his older one....any help would be appreciated!
    Last edited by driver99; 08-10-2012, 04:52 PM.
  • AmickRacing
    Senior Member
    • Feb 2008
    • 235

    #2
    I really think the easiest thing to do would be adjust the car. Shouldn't take much... less preload on the 5th arm, or a distance change. Of course, I'm not dealing with them, so that could be the hardest option lol

    Are you running a spacer under the carb? If so take it out, if memory serves me right it should take some bottom away and give you more top end. Trying new headers might work also, course it could make it worse too, just depends on how the whole package works together. If you have a set, I'd sure as heck throw them on and give it a shot.

    I believe someone (TechWest?) makes a coil wire that de-rates the spark, sort of like traction control, but not adjustable, just kills power.

    Could you change gears some? Either go up a bit so he can control it better with his foot (easier said than done of course), or take some away so it's not quite in the torque range right out of the corner. That's kind of a terrible idea (changing gears, assuming your close), but it seems like they are avoiding the proper things to change.

    Another thing to double check, make sure the carb linkage is set up properly. Going down on the pedal arm can make the driver have to move his foot farther than he is now. This can either make it easier to control, or his muscle memory will make him feel like he's going half throttle when he's actually going a bit less.
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    • perfconn
      Senior Member
      • May 2007
      • 3573

      #3
      Change the headers,take some timing out,tighten the valves up not loosen,put an open 2 inch spacer on.Those are the easy things,moving the cam will do more but is harder to do.Puting a bigger carburetor on will kill torque also.

      Comment

      • 50j
        Senior Member
        • Jun 2007
        • 1047

        #4
        Headers, cam change, go to gas, pedal travel, slow down secondary side on carb even more, make car work, replace driver or motor.

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        • driver99
          Senior Member
          • Aug 2007
          • 106

          #5
          I'm gonna push for the header change as I think they might listen to that. As for the ignition timing how far back should that go, I'm thinking try 28 first but???? Cam timing might be an option if the car owner can be convinced, do you think going straight up to 107 is enough?I also had a feeling that tightening lash could be the answer versus loosening it, but how much? Maybe go down to .014 .016? Thanks again for all the advice, it is confirming that my thinking is in the right direction. Also the taller spacer is not an option due to rules...

          Comment

          • autoshop
            Member
            • May 2007
            • 58

            #6
            drop the timing down, try slowing the throttle pedal ratio down or use a throttle sponge.

            Comment

            • perfconn
              Senior Member
              • May 2007
              • 3573

              #7
              Don't know much about your driver but that engine ought to be a dog with the cam in at 105*. I normally use a 108* cam with alcohol with the intake lobe on 104* Moving the cam to 107* will help a little but I think you will need some of the other changes to be able to flatfoot it.

              Comment

              • sj valley dave
                Senior Member
                • May 2007
                • 1016

                #8
                I agree with Perfconn... @ Amick racing...taking the spacer off will reduce the plenum size which will increase the "snap" and torque...By going to a larger spacer you will soften the bottom and increase the top end...We run a 2" open spacer in our SB2.2 to help with the bottom..as far as timing we have 2 boxes, coil, etc and run the primary at 30.5* for paek HP...2nd is at 27*..kills about 75 ft lbs....

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                • driver99
                  Senior Member
                  • Aug 2007
                  • 106

                  #9
                  Thanks for all the replies!! At least I feel a little better about this deal. Perfconn I'm glad you don't think it should be too wild a engine as I kinda agree..... . Gonna push for a couple of the changes for tonight's race and see if I can move things a direction the driver is happier with.
                  Last edited by driver99; 08-10-2012, 04:54 PM.

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                  • 700horsepower
                    Senior Member
                    • Dec 2007
                    • 191

                    #10
                    This adjustable Governor will remove as much power or edge as needed without any other changes to the engine.
                    Our race car parts are designed with precision engineering for unbeatable performance on the racetrack.

                    Comment

                    • 500BOMBER
                      Senior Member
                      • Jun 2007
                      • 762

                      #11
                      Stomp on the drivers foot before he gets in the car. Then , he wont push the throttle so hard, 'cause his foot hurts.
                      Old enuf to know better, still too young to givadamm.

                      Comment

                      • Egoracing
                        Senior Member
                        • May 2007
                        • 4852

                        #12
                        Put stiffer springs on the pedal, put them were they are not pulling on the carb but on the pedal so it is harder to push, this will make the driver pay more attention to the pedal and not stomp it to the floor. Several years ago someone made a shock for the gas pedal that would relax when "hit" and then go back to normal. The rate of changed was controllable with an air bleed, a lot of people ran them on asphalt for a few years.

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                        • turner
                          Senior Member
                          • Apr 2008
                          • 193

                          #13
                          If you are just looking to kill horsepower, unhook the secondarys on the carb. I know people will say it wil run lean etc, but you will have half the fuel and half the air. I did this for 10 years at the dragstrip on a 455 buick engine. It ran 11.20's at 120 mph at 3850 lbs and when i unhooked the secondaries, it would slow to 12.00's at 111, which is the class i wanted to run. This was on a 850 double pumper.Just an idea.Good luck with what ya try.

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