Off idle bog issue

Discussion in 'Technical' started by ptpdub, Aug 21, 2017.

  1. ptpdub

    ptpdub Member

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    Here's the situation. If I accelerate away Slowly the vehicle response very well, if I jump on it in order to spin the tires I instantly bog out and it sounds like a drop a few cylinders. Once the RPMs come off a little bit, I take off like a rocket. 302, gt40p heads Lift: .498''/.498'' Duration @ .050: 220°/220° Advertised Duration: 282°/282° Camshaft. 600 cfm Holley, c4. I borrowed an identical carburetor from an identical engine that performs very well and bolted it on to my engine. My engine took off like a rocket and performs the way I want it to. My question is this, is an off idle bog always accelerator pump related? Where else should I look?
     
  2. dyent

    dyent Member

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    keep the borrowed carb and return yours.........:rofl2:
    David
     
  3. ptpdub

    ptpdub Member

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    Nooooow there is an idea!
     
  4. Krazy Comet

    Krazy Comet Tom

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    Sounds like you may have a delayed pump shot...

    Check to see when the squirters supply fuel and for how long... If you still have the borrowed carb, check it as well...

    BTW low float level can give similar symptoms...

    BTW #2 if none of above helps, keep the borrowed carb... ;)
     
  5. ptpdub

    ptpdub Member

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    Seems like a plan I can get behind.
     
  6. Crazy Larry

    Crazy Larry Member

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    Is this a new problem or has it been happening since the carb was first installed?
    Not only could the accel pump be bad, you may need a different size discharge nozzle. Make sure the plastic pump cam
    is the orange one, and the screw is in the #2 position. As mentioned before, check float levels. Make sure accel pump lever is adjusted so that there is .015" clearance between pump arm and spring at wide open throttle.
     
    Maverick Dude likes this.
  7. 71gold

    71gold Frank Cooper Supporting Member

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    another one of all the carb problem reasons I went EFI...:drive:...:chirp:
     
  8. Krazy Comet

    Krazy Comet Tom

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    And just how is this fixing his bogging problem???

    Are you gonna buy him a EFI system??? How bout the rest of us???

    Fairly obvious after 35 years of fuel injection systems those are superior to carbs, at least till you have to troubleshoot one... I've worked on lots of stuff at a buddies car lot & hung out on enough late model boards to know for every carb problem there can be 5-10x problems when dealing with EFI...
     
  9. 71gold

    71gold Frank Cooper Supporting Member

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    "Fairly obvious after 35 years of fuel injection systems those are superior to carbs"

    it fixed any carb problems I will ever have.
    I liked your suggestion of... #2 if none of above helps, keep the borrowed carb......:thumbs2:
     
  10. ptpdub

    ptpdub Member

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    I would say the problem develops slowly over time. I don't drive it much, The engine and carb are 8 years old.
    One other problem that I should have mentioned is that when the engine is warm, if I shut it off, in order to restart the engine I must hold it to the floor while I crank it. Even then it takes a few seconds to fire.
     
  11. ptpdub

    ptpdub Member

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    May I ask what Efi you are using?
     
  12. 71gold

    71gold Frank Cooper Supporting Member

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  13. Crazy Larry

    Crazy Larry Member

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    The difficult restarting is due to ethanol in the gasoline. It boils in the fuel bowls and causes flooding when hot. This was never a problem before ethanol was added to gasoline. Fuel injection systems are not affected by this.
     
  14. Krazy Comet

    Krazy Comet Tom

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    Gas is reformulated from winter to summer, back to winter to increase/decrease boiling point... I'd bet boiling point is much the same as it's been for last 50+ years... Depending on formulation, vaporization temp can be anywhere from 100*F to over 350*F..

    Summer gas in winter temps causes starting problems as it doesn't vaporize as easily... Winter gas will likely boil off on a hot summer day when temp is 90* and engine is at 210*...
     
  15. Crazy Larry

    Crazy Larry Member

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    Nope. It's the same all year-round. 20 years ago the E10 was used between October and February only, but all that has changed. It is done to subsidize the corn industry. Has a lower boiling point than pure gasoline. It's crap.
     

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