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    Results 21 to 28 of 28
    1. #21
      Join Date
      Oct 2014
      Location
      DFW, Texas
      Posts
      422
      Country Flag: United States
      Quote Originally Posted by Mr Nick View Post
      Are those vacuum actuators "tune-able" to open at a different point?
      No sir. Wish there was some adjustment there.
      1972 Plymouth 'Cuda - Not LS-swapped, 5.7L Hemi [MS3 Gold Box], T56 Magnum 6-speed - 'Cuda Build Page
      1976 Dodge D100 - Warlock
      2016 Subaru WRX - E30 Tune

    2. #22
      Join Date
      Aug 2008
      Location
      jacksonville,fl
      Posts
      970
      Country Flag: United States
      I have zero experience with vacuum actuated exhaust valves, but here's a few thoughts::::
      An example would be on older GM ac/ heat systems you had a large ball which was a vacuum reserve. Maybe some sort of small canister(adjustable size would be nice) that would save just a little vacuum to make them seem less sensitive.
      Probably the only way the valve could be made tunable would be to restrict it , which I think would just make it close slower. Not sure if restriction would make it also open slower??? To have the opposite effect, you'd need to add vacuum.
      I'm pretty sure the average vacuum canister consists of whatever air volume it offers & a check valve to not let vacuum bleed back out to manifold source. Based on that thought, maybe a canister with it's check valve could be installed inline ( Parallel ) with the main feed to offer some effect of momentary continued vacuum as the cannister bleeds down.
      Another much simpler possibility of adjustment would be a tiny pull spring hooked up to the valves to help them in the stay closed direction, thus effectively retarding the vacuum drop effect.
      Just a dumb thought from a high school only educated idiot that thinks more than sleeps.

      Anybody got any better ideas? Bill?

    3. #23
      Join Date
      Oct 2014
      Location
      DFW, Texas
      Posts
      422
      Country Flag: United States
      So far I’m going to drive it as is and see how the valves hold up before getting too fancy.

      I may install a boost controller valve to help manage the cutout. I can switch it to allow them to always be open, and I think I can get it to run a check valve and keep the valves closed. They don’t really bleed off on their own.
      1972 Plymouth 'Cuda - Not LS-swapped, 5.7L Hemi [MS3 Gold Box], T56 Magnum 6-speed - 'Cuda Build Page
      1976 Dodge D100 - Warlock
      2016 Subaru WRX - E30 Tune

    4. #24
      Join Date
      Aug 2008
      Location
      jacksonville,fl
      Posts
      970
      Country Flag: United States
      Honestly I think that sort of setup would be more useful, being able to be fully open or fully closed when you want. There are plenty of times when you want to dip into throttle without drawing excessive attention or have that loud idle. I'll probably build me a better cable operated valve on my next exhaust.

    5. #25
      Join Date
      Feb 2007
      Location
      Tinley Park, IL
      Posts
      1,163
      Country Flag: United States
      I was thinking there may be a simple adjustment to have them open at different vacuum signals, similar to a vac advance canister on a distributor. The KISS method may be a spring to delay/slow the opening points, like jlkustomz mentioned.

      With a little tinkering, one could have a Helmholtz chamber and an active exhaust for far less than this kit, albeit with much less adjust-ability as well. https://www.holley.com/products/exha.../71013001-RHKR

      Nick ~
      1969 Cutlass

    6. #26
      Join Date
      Apr 2004
      Location
      Cedar Rapids, IA
      Posts
      999
      I changed mufflers from a straight through design to a the super turbos, this reduced the drone but still there. Then i moved to the VT mufflers. Sad that they are a thing of the past now, because they worked great for me.

      Some times I'm fast sometimes I'm half-fast


    7. #27
      Join Date
      Sep 2004
      Posts
      159
      Country Flag: United States
      Here’s a great YouTube video explaining the Helmholtz resonator. It has links to a nice spreadsheet to help calculate your size requirements.
      https://youtu.be/z5SY5oUTEcc
      Brian P

    8. #28
      Join Date
      Sep 2020
      Posts
      4
      Thanks Goody, I’m trying to resolve a 50mph drone, I’ve tried different mufflers, H pipe and X pipe and I currently have the Magnaflow system I had on my Cuda that had absolutely no drone at all, same system on my my 67 it drones like a B******, only difference is the 67 has factory performance manifolds, the cuda had TTI headers, so right now I’m looking at installing resonators in the engine pipes ahead of the X pipe ��*♂️

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