Quick fuel carb issue

Fuel and Air Systems

  1. chargermll

    chargermll Member

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    I'll try to explain this the best I can. For the past couple of months I have been getting my 72 Charger back together. I have a 950 QF carb on my stroked 440. This is a brand new carb that I put on my brand new engine. I did the general tune and fired the engine up. The only issue I had with this carb was that it was rich at idle. I played with the IFR's and IAB's to try to fix that issue. It got better but not perfect. I decided to try a smaller IFR. Did that, put the carb back on and now I can't get it to idle. Took carb off, put back to previous set up. Still having same issue. I double checked that my transfer slots were "squared" on both the primary and secondary. Double checked float levels. Both in the middle of site glass. I cleaned everything with carb cleaner and blew out the passages with compressed air. My timing is at 25 degrees initial. Changing timing has very little effect. The engine starts fairly easy and I can keep it running if I keep my foot on the pedal but its rough and dies as soon as I let off. I discovered that I can get it to idle( but very poor) if I pull the pcv hose off and create a vacuum leak. What I found out after doing this was that if I turn the idle mixture screws in the completely on the primary it has no effect, engine keeps running. If I turn the screws in on the secondarys then the engine shuts off like it should. So I'm thinking some how gas is leaking into the primary. I tried cleaning the primary's again. No change. I have an electric fuel pump. I have it set at 6 psi according to the gauge. I dropped it down to 4 psi and still no change. At this point I'm out of ideas. I'm sure this is something simple that I am just missing. I'm open to any ideas. Thank you
     
  2. texas69bee

    texas69bee Well-Known Member

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    I’m no expert at this but here’s a few things I’ve learned. I believe if the idle didn’t change with your primaries than your power valve may be bad.
    Do you have the correct size? Size is = to 1/2 your vacuum.
    When you reinstalled your carb, did you readjust your linkage and idle screw?
    Where is your vacuum from your distributor hooked up to? Port or Manifold? Make sure you physically look at how the ports are routed through the carb, the instructions online instructions on the Holley website are wrong.
     
  3. 747mopar

    747mopar FBBO Gold Member FBBO Gold Member

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    What's the vacuum measure? The idle circuit works off of vacuum so little to no vacuum would create some problems with the circuit. Might also check the power valve and make sure it's not opening at idle too which also goes back to vacuum.
     
  4. chargermll

    chargermll Member

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    I actually put a different power valve in to see in it made a difference. I went to a 2.5 to a 3.0. I know the 3.0 was never used. I never had the vacuum advance hooked up. I checked linkage and double checked my idle screw to verify the transfer slots were "squared".
     
  5. texas69bee

    texas69bee Well-Known Member

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    As 747Mopar asked... what’s your vacuum?
     
  6. chargermll

    chargermll Member

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  7. chargermll

    chargermll Member

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    Around 7 inches of vacuum at idle. When in "drive" rpm went to 800, then had about 5 inches of vacuum. I had a 2.5 PV in it.
     
  8. texas69bee

    texas69bee Well-Known Member

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    The next best thing I would suggest is to hit YouTube. There is a lot of useful videos on there. Holley owns QuickFuel now and most of the videos apply to each other.
     
  9. chargermll

    chargermll Member

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    I actually started doing that and searching for similar issues on google.
     
  10. texas69bee

    texas69bee Well-Known Member

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    Where are you measuring the vacuum at and with only 5 in of vacuum, you must have a pretty radical cam?
     
  11. chargermll

    chargermll Member

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    Its a comp cam solid lifter. 567/579 lift. duration at .050 264/270
     
  12. chargermll

    chargermll Member

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    Basicly as soon as i start it, it dies. I can put my foot on the gas pedal and hold the rpm's at 1,000. As soon as I let off it dies. It started doing this after I made an IFR change. I was trying some things this evening and still the same result. The only way I can get it to idle is with the primary mixture screws turned all the way in and the pcv hose disconnected from the carb. Now if I turn the idle mixture screws in on the secondaries the engine will shut off. Some how extra gas is flowing in the primaries. I just ordered a rebuild kit. The only thing I have not done is change the bowl and metering block gaskets.
     
  13. texas69bee

    texas69bee Well-Known Member

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    When you tighten down the bowl, make sure your just snugging things up. Don’t over torque.
    I’m wondering if you need a larger power valve than stated. That’s why I asked where you measured the vacuum at. It sounds like the power valve may be held open and allowing fuel to flow.
    You could also call Holley Tech Support
     
  14. HEMI-ITIS

    HEMI-ITIS STREETER FBBO Gold Member

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  15. chargermll

    chargermll Member

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    I'm usually pretty easy on tightening the fuel bowls but it's a possibility I might have over torqued them. Last night I actually took the power valve plug out of the secondary metering block and installed it in the primary block and still the same result. If I still have the same result after a carb rebuild, the tech line will be my next step.
     
  16. chargermll

    chargermll Member

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    Yeah I definetly set the fuel bowl levels. My carb also has the large site glass. I was setting both float levels at the middle of the site glass. That is where I thought the quickfuel level was supposed to be set at. I know on a holley the fuel is supposed to just trickle out of the hole. I also pulled out the needle and seat. I sprayed it with carb cleaner and hit it with compressed air. My rebuild kit should come tomorrow. I'll see if that makes a difference.
     
  17. chargermll

    chargermll Member

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    Just an update. I did a rebuild on my Quickfuel carb and still have the same issue. When I ordered my Quickfuel kit, I also ordered a rebuild kit for an old 850 double pumper that I had. Installed the rebuilt 850. Other than chasing a few gas leaks that carb is working great. I am going to call Holley some time next week and speak to them about the issue I was having. Maybe I can send it to them and have one of there experts look at it.
     
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    • texas69bee

      texas69bee Well-Known Member

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      What size power valve in the other carb?
       
    • Bigal75

      Bigal75 Well-Known Member

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      So have you raised the idle? If you say you can keep it running at 1000 rpm with your foot on the throttle then raise the idle. Make sure the transfer slot is square on the primary side and adjust the secondary so it can idle.
       
    • Bigal75

      Bigal75 Well-Known Member

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      And there's no way you want a 2.5 power valve on there. Go for a drive with a vacuum gauge and see what the gauge reads on a flat road while cruising in high gear. I bet it's a lot higher that 5" or 7". I'm guessing 12 to 15, so I would try a 10, 9 or 8.5 PV. And no it won't screw up your idle
       
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