Stumble @ Cruise

Discussion in 'The "Other" Bench' started by DeeVeeEight, Sep 29, 2019.

  1. DeeVeeEight

    DeeVeeEight Well-Known Member

    I have a fresh 355 with a mild build (355 hp, 390 tq.) roller cam, 9 to 1 compression, air gap intake manifold topped with a Holley 4150, mechanical secondaries. Vacuum is at 16 inches, idle @ 750 rpm. Idle is great and the engine runs strong and smooth. The engine is in a '79 Corvette with a manual transmission.
    When cruising on the highway, if I accelerate lightly there is a bit of a stumble. I have been doing a bunch of internet reading but this is where I come for the answers I trust. I am leaning towards the primary jets being too lean. At first I found that the accelerator pump was out of adjustment and I have that back within specs (as far as I can tell) and it has helped a lot - but the stumble, though less noticeable is still there. Your thoughts as always, are appreciated.
  2. johnriv67

    johnriv67 Well-Known Member

    Yeah I’d step it up two jet sizes in the front. That’s a great way to try and tune it out.
  3. johnriv67

    johnriv67 Well-Known Member

    It's a Holley 4150 though.
  4. techg8

    techg8 The BS GS

    LOL wow I missed that thanks! Quadrajets on the brain...….
  5. johnriv67

    johnriv67 Well-Known Member

    I'd rather have those on the brain too, but I'm learning to adapt to different things lol

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