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Sunday morning bench race - Valve springs and rev kits - pros and cons?

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  • #16
    Re: Sunday morning bench race - Valve springs and rev kits - pros and cons?

    Originally posted by Tom Slick
    uh, where did you guys get DOHC from a pushrod conversation?
    just that most that think pushrods are stoneage
    look to the Dohc as the end all

    Comment


    • #17
      Re: Sunday morning bench race - Valve springs and rev kits - pros and cons?

      I seem to remember some guys I knew that had a rev kit on a BBC drag car,9.50's in 1978,went 7's in a dragster.

      IIRC they where outlawed in many racing classes,including NASCAR,and Most NHRA class's. So they must have done something at one time.

      Just to the eye they seem to make sense,the lifter,and push rod get there own spring,the rocker and valve it's own. But I also see all hell braking loose when the pushrod comes out of rocker....

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      • #18
        Re: Sunday morning bench race - Valve springs and rev kits - pros and cons?

        I like on the sohc dodge 4.7 , the lifter sticks in the head and the rocker arm follower falls off
        the 4.7 makes no power anyway

        ohc , you get crappy timing belts or overcomplicated , stretchy timing chains that are a half a mile long

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        • #19
          Re: Sunday morning bench race - Valve springs and rev kits - pros and cons?

          That's what I'm questioning - a big part of the springs responsibility is to keep the lifter on the lobe. Let the rev kit handle part of that and reduce the load on the valve spring. If you can get a lighter valve package and the lifter cam do their own thing, it doesn't necessarily need as much spring?

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          • #20
            Re: Sunday morning bench race - Valve springs and rev kits - pros and cons?

            Originally posted by Tazracing
            Originally posted by Tom Slick
            uh, where did you guys get DOHC from a pushrod conversation?
            just that most that think pushrods are stoneage
            look to the Dohc as the end all
            Pushrods gentlemen. Derail the Car Craft thread instead please.

            /edit -

            Low buck testing - do y'all think it would be valid to take a matched / recommended setup from a company like Comp, ie, their cam, spring package, etc. matched to a certain cam, then replace with lighter springs, rev kit, and see if it doesn't rev as clean or run as well?



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            • #21
              Re: Sunday morning bench race - Valve springs and rev kits - pros and cons?

              Originally posted by Tom Slick
              Originally posted by Tazracing
              Originally posted by Tom Slick
              uh, where did you guys get DOHC from a pushrod conversation?
              just that most that think pushrods are stoneage
              look to the Dohc as the end all
              Pushrods gentlemen. Derail the Car Craft thread instead please.

              /edit -

              Low buck testing - do y'all think it would be valid to take a matched / recommended setup from a company like Comp, ie, their cam, spring package, etc. matched to a certain cam, then replace with lighter springs, rev kit, and see if it doesn't rev as clean or run as well?



              Again the rev kit DOES NOT add spring pressure to the valve, it's only purpose is to keep the lifter in the bore in case of a pushrod or rocker failure.

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              • #22
                Re: Sunday morning bench race - Valve springs and rev kits - pros and cons?

                TC the set up I've seen has a groove and retainer on the pushrod,just like a valve spring retainer, so it is carrying the lifter and pushrod load.

                I have to think,unless there is a rule against it,modern spring packages must negate thier need or every Pro Stock and NASCAR team would use them.

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                • #23
                  Re: Sunday morning bench race - Valve springs and rev kits - pros and cons?

                  the Chet Herbert rev kit does not have a groove or " keeper " on the push rod.
                  Reading , Pa
                  Good Guys rodders rep.
                  "putting the seat down is women's work" Archie Bunker.
                  Ban low performance drivers not high performance cars .

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                  • #24
                    Re: Sunday morning bench race - Valve springs and rev kits - pros and cons?

                    Going back twenty years, the large by hugwe solid cams and the newer designed, fast opening ramps were beyond the control of valve spring tech. The only way to control valve float, or ligher valve springs from snapping was insane spring pressures. Add to to that high revving rpms, cams and lifters were dying. Solid roller lifters lasted maybe one season.

                    CAD designing, computer modelling, and most importantly, vastly improved materials, like titanium, have allowed rev kits and crazy triple valve spring pressures to ease. I've been told by more than one cam tech that you should use the lightest spring to control valve timing and float. The use of better designed springs and lighter materials to keep weight down, ie titanium retainers and springs.

                    I was watching drag week, and the bad ass '57 Chevy kept eating roller lifters and other valve train issues, I kept wondering if old school valve train thinking was hurting them.
                    BS'er formally known as Rebeldryver

                    Resident Instigator

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                    • #25
                      Re: Sunday morning bench race - Valve springs and rev kits - pros and cons?

                      Originally posted by TubbedCamaro
                      Originally posted by Tom Slick
                      Originally posted by Tazracing
                      Originally posted by Tom Slick
                      uh, where did you guys get DOHC from a pushrod conversation?
                      just that most that think pushrods are stoneage
                      look to the Dohc as the end all
                      Pushrods gentlemen. Derail the Car Craft thread instead please.

                      /edit -

                      Low buck testing - do y'all think it would be valid to take a matched / recommended setup from a company like Comp, ie, their cam, spring package, etc. matched to a certain cam, then replace with lighter springs, rev kit, and see if it doesn't rev as clean or run as well?



                      Again the rev kit DOES NOT add spring pressure to the valve, it's only purpose is to keep the lifter in the bore in case of a pushrod or rocker failure.
                      Not much to "Again" here - this was never a question of the lower springs (rev kit) controlling the VALVE. The question is - by controlling the lifter with a secondary spring of suitable pressure, you don't have to exert so much pressure to control the valves. If you don't have to sweat keeping the lifter on the ramps, you can lighten up your valve package and lighter is better, right?

                      I'm pretty sure all this modern roller stuff is aggressive as hell and thinking out loud - it might be worth a test, it's not all that much coin. I'd venture a twelve pack that you can get the same RPM with lighter springs... All good chat. Thanks guys.

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                      • #26
                        Re: Sunday morning bench race - Valve springs and rev kits - pros and cons?

                        not quite, the spring is KEEPING the valve closed when it closes so it doesn't bounce off the seat.. at that time the lift and pussrod and rocker have no weight on the spring or valve..
                        light'n spring with your "rev kit" the valve will float.. as the spring at float is only controlling the valve not the whole valvetrain..
                        if it slammes shut and reopens.. it wasn't the weight of the pushrod/rocker/lifter..
                        they are already off the spring by then...

                        Comment


                        • #27
                          Re: Sunday morning bench race - Valve springs and rev kits - pros and cons?

                          there was the truLINK the nascar boys used to run , mark is right those had a keeper type groove
                          http://www.decuirenginetechnologies.com/trulink.php

                          not sure if they still run it

                          Comment


                          • #28
                            Re: Sunday morning bench race - Valve springs and rev kits - pros and cons?

                            Originally posted by Cyclone03
                            TC the set up I've seen has a groove and retainer on the pushrod,just like a valve spring retainer, so it is carrying the lifter and pushrod load.

                            I have to think,unless there is a rule against it,modern spring packages must negate thier need or every Pro Stock and NASCAR team would use them.

                            The springs in the rev kit are basically the inner spring of a dual spring setup and at that they do not have a lot of spring pressure. Also how would you get a retainer around a pushrod when the spring is sandwiched between the head and the lifters. I'd really like to see this setup your talking about, got a link?? Because it's definitely not like rev kit that came with my cam package from Crower.

                            The fact is when the valve is closed the spring on the rev kit does nothing to the spring pressures at the valve, so going to a weaker spring at the valve will reduce your closed pressure and you'll end up with valve float earlier in the RPM range.

                            And as for when the valve opens the only thing seeing any more spring pressure is the lifter, which is a good thing since it will keep the lifter on the lobe of the cam so that the motor can rev higher RPM's. Hence the name "Rev Kit". ;) Remember reducing spring pressure reduces the amount of RPM a motor can spin. ;)

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                            • #29
                              Re: Sunday morning bench race - Valve springs and rev kits - pros and cons?

                              Originally posted by SpiderGearsMan
                              there was the truLINK the nascar boys used to run , mark is right those had a keeper type groove
                              http://www.decuirenginetechnologies.com/trulink.php

                              not sure if they still run it
                              But that kit does not allow the spring to rest on the lifter, the spring basically sits on a retainer on the pushrod.

                              And I'm not sure I'd want to put a groove in the middle of a pushrod that has to support 600lbs of spring pressure. ;)

                              Comment


                              • #30
                                Re: Sunday morning bench race - Valve springs and rev kits - pros and cons?

                                I'm not convinced that you have to keep the same valve spring pressure, but I'm with milkovich. Without something to see what is happening, this is all academic anyway.

                                Maybe a rail would be a good test vehicle for goofy questions like this? That'd be somewhat empirical.

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