Solved my stumble/ hesitation issue

Discussion in 'Small Block Tech' started by Mark Demko, Jun 30, 2020.

  1. Mark Demko

    Mark Demko Well-Known Member

    I watched a you tube vid from Thunderhead 289, best explanation I’ve seen about Holley accelerator pump operation. I had NO idea that when you alter your curb idle, you also need to check your pump arm. I had lowered my idle a tad last year, and not knowing that doing that will make the pump arm sloppy, you have to re adjust to take up the slack which obviously causes stumble.
    I learned something :D:D
    MrSony, alec296, Dano and 5 others like this.
  2. patwhac

    patwhac Well-Known Member

    Glad to hear you were able to fix it!

    You know I should probably start a new thread or ask this on my build thread . . . but what the heck haha!

    Is there anything I should do to a used Holley Vac Secondary 600cfm to ensure that my motor fires up right away for cam break in? Apparently it had a bad accelerator pump gasket that cause the car it used to be on to have "no acceleration" and was fixed and is now "ok". It was lent to me by a friend for the break in.

    I was planning on filling up the bowls with fuel and letting 'er rip. Anything else I should do (besides watch that youtube video)?
    Mark Demko likes this.
  3. 73 Stage-1

    73 Stage-1 Dave

    You really want to eliminate any and all variables that you can think of. I'd at least bolt the carb to something else to make sure it's going to work right, and be adjusted close (idle screws, float levels, etc). First start up is critical, you don't want to leave anything to chance - especially with a borrowed carb. My .02.
  4. patwhac

    patwhac Well-Known Member

    Mmm I was thinking about trying to bolt it to something else, problem is I don't have anything else to bolt it to! My old coworker with a 1975 Ford truck said he'd let me if it wasn't his only set of wheels . . . Anyone wanna let me run my carb on their engine for a 6 pack haha?
  5. Mart

    Mart Gold level member

    I wouldn't use a vac secondary Holley, especially only a 650, or a 650 anything on a 350. Tried a 750 years ago and played with the quick change vac sec spring setup. Still sold it in favor for a double pumper.
    Just my experience....
    Mark Demko likes this.
  6. patwhac

    patwhac Well-Known Member

    I wasn't planning on driving with it, just using it for cam break in! Though I do have an SP3 (will go EFI), do they like small or big carbs? Also, sorry Mark for thread hijacking!
    Mark Demko likes this.
  7. MrSony

    MrSony Well-Known Member

    Met thunderhead at good guys. He was there with his galaxie. Nice dude.
  8. Mark Demko

    Mark Demko Well-Known Member

    From his vid he seems like it, He explained very well, plus his dog was in the vid:D
  9. Mark Demko

    Mark Demko Well-Known Member

    HAHA, its cool Patrick, I don't consider it hijacking, your just asking a related question, which contributes to the conversation:cool:
    Listen to Mart about the carbs, and myself LOL, When it comes time to drive it, DO NOT use a vacuum secondary carb, even a Q-Jet will flat blow away a vacuum secondary Holley.
    Use AT LEAST a 750 double pumper on an SP3, I tried a Q-Jet on mine, it was fine for driving and WOT, BUT even tho the Q-Jet is a mechanical secondary, there is no dedicated secondary accelerator pump like a Holley "double pumper" (that's where the double pumper name comes from) so when you slam the throttle open on a Q-Jet when its on an SP3 you get a few seconds of a lean condition and the engine feels like it shuts off, you can probably tune it out with the tension on the upper air flaps, but that kinda defeats the purpose of the SP3.
    I went to an 850 AED double pumper, Summit told me that's WAY to big for a 350:rolleyes::rolleyes::rolleyes: WHATEVER LOLOLOL
  10. Mark Demko

    Mark Demko Well-Known Member

    Mart, I have a 750 Vac Secondary Holley you interested? Its for sale:p:p:p
  11. Mart

    Mart Gold level member

    :D Those are made for chebby guys..:D Put it on your mantle...

    DEADMANSCURVE my first word : truck

    i have "chevy guys" look for 750VS carbs . let me me know how much .
    warning : i don't pay big money for them .

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