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SOLVING LOW IDLE

Discussion in '308/328' started by absostone, Jul 28, 2019.

  1. absostone

    absostone F1 Rookie
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    It was from where it was set originally . Not from 3 turns out. I was just playing around. Found it odd. I’m still learning the carbs.
     
  2. absostone

    absostone F1 Rookie
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    So I’m thinking to check the type of mixture screws I have ,,,stepped / tapered. And maybe float height?
    Just throwing ideas out
     
  3. Saabguy

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    With Webers if you change the mixture screw and the idle speed doesn't change (Up or down) you are likely running on the "run" circuit and not the "idle" circuit. That would also explain why you have so much air going in.

    Have you started from scratch where you VERIFY with a flashlight that the butterflys are actually ALL the way closed?

     
  4. absostone

    absostone F1 Rookie
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    Looks like They are closed. So your saying it’s running on the mains?
     
  5. Saabguy

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    #55 Saabguy, Aug 6, 2019
    Last edited: Aug 6, 2019
    Yeah basically, that explains some of your symptoms. "Looks like" isn't the same as "are closed". The purist in me says that you need to take the carbs off, back off all the screw and shine a light from underneath to verify that the butterflies are closed, this may not be practical though.

    Back off ALL of the idle speed screws so that they aren't touching, engine should NOT be able to idle at all, if it is idling then you likely have a linkage adjustment problem. Then start with the 2 or 3 turns just to get it to idle then go through the process of mixture adjustment. Granted my knowledge is Weber based NOT Ferrari Weber based, but I am certain that they still have Idle, run, and WOT circuits.
     
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  6. absostone

    absostone F1 Rookie
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    #56 absostone, Aug 6, 2019
    Last edited: Aug 6, 2019
    I’m gonna recheck in s little while. And yes I was gonna try turning them in to see if it choked it. I meant the mixture screws
     
  7. absostone

    absostone F1 Rookie
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    Maybe the butterflies are dragging on the bores
     
  8. absostone

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    How would it idle without the stop screws?
     
  9. absostone

    absostone F1 Rookie
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    These carbs look like they are 20 yrs old rebuild. They have about 1k miles if that
     
  10. absostone

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    From what I know the idle jets are in play till around 3k
     
  11. Saabguy

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    It should ONLY idle that way IF there is tension in the linkages or the throttle cable. If it doesn't idle then you have eliminated one concern.

    After you have confirmed that then you turn in the idle speed screws until it will idle then the mixture screws until it idles well, make sure that there is no connection of one carb to the next. Get the engine idling well and THEN connect all the carbs to each other

    That said, I reread the entire thread and you started with ignition concerns, are those gone now?

     
  12. absostone

    absostone F1 Rookie
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    Yes it’s around 7-9 deg advance at 1k
     
  13. absostone

    absostone F1 Rookie
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    I set the idle the Birdman way. Brought it down to 1k from 1500. Then set the idle stops. I just turned out the screws. And it was nerve racking idling that low. Pretty sure both idle screws were as loose as good be. It still idled barely. Throttle cable still had plat btw
     
  14. absostone

    absostone F1 Rookie
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    When individual mix screws are turned in all the way the idle does drop. Barely
     
  15. absostone

    absostone F1 Rookie
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    So is it really possible that every butterfly is slightly open and allowing it to suck air at idle? A pro shop built these. Unreal
     
  16. Saabguy

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    Yup, the idle circuit. Find the other diagram with the run or partial throttle circuit.

     
  17. Saabguy

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    If ALL the idle screws are TURNED IN ALL THE WAY it should not idle at all. There would be no fuel going in to the engine unless you are idling on the run circuit or some other source of fuel.

     
  18. Saabguy

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    It is more likely that the rebuilder put things back together incorrectly and that is keeping the throttle plates from closing OR there is a screw somewhere that is keeping them open by design that you are missing.

     
  19. absostone

    absostone F1 Rookie
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    Yea but every carb? Bent shafts? I’ll try everything in.
     
  20. absostone

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  21. absostone

    absostone F1 Rookie
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    Man if these carbs gotta come off I’m gonna flip out something evil!!! This is bs
     
  22. Saabguy

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  23. absostone

    absostone F1 Rookie
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    I believe there are only to circuits. Low and high. Idle and main. Am gonna try that next. Thx
     

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