QJ major stumble at high RPM

Discussion in 'The Venerable Q-Jet' started by ravensbud, Sep 29, 2017.

  1. HotRodRivi

    HotRodRivi Tomahawks sighted overseas

    im sure anyone with a dyno like JW will know how much should be in the bucket. You would be able to tell if your flow peters off though. If you start strong you should finish strong. We are talking electric fuel pumps, . Ha Ha Larry I believe my subconscious had that chassis manual opened to that page so I could have that revelation. I know there are equations you can plug the nums into and come up with an amount or range to be in.Can valve springs floating have the same affect.? You are falling on your nose at the top of the gear.
     
  2. HotRodRivi

    HotRodRivi Tomahawks sighted overseas

    A couple full throttle runs resulted in same thing....pressure crashes quickly to 2-3lbs above 5k in second gear, engine stumbles and I quickly get out of it.

    Whats hapening to the voltage during all this. An electric pump with a return line dosent care what gear or rpm your in, it will humm along regardless. That would be funny if your problem all along was a loose wire . An electronic hiccup.
     
  3. ravensbud

    ravensbud Silver Level contributor

    This is a mechanical pump. As stated earlier, RobbMc 1100hp version. Theoretically should work just fine, but as Cliff has related sometimes the best mechanical setup just doesn’t cut it in a particular car.
     
  4. HotRodRivi

    HotRodRivi Tomahawks sighted overseas

    This tread has wrongly assumed the problem was with the QJ carburatior. The Qjet is above that and does not feel offended. Qjet is quite used to that.
     
  5. ravensbud

    ravensbud Silver Level contributor

    To update, I ended up going with Tanks Inc. TM37J-T EFI Fuel Tank Kit, 1964-67 Buick Skylark. Awesome powder coated tank fit great, is baffled and has a “sump” where the pump sits. 24 gallon capacity. This is for an efi setup and I have a QJ so I put a return regulator mounted on trunk pan just above the tank and also kept the deadhead regulator in place up front.

    Fuel delivery issue solved! Idles at 8 psi and never drops below 6.5 psi above 5000 rpm. Thanks to Cliff and others for relating your experiences in this thread.
     

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