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308 Carb Spitting/Ticking noise

Discussion in 'Technical Q&A' started by Sean F., Mar 23, 2004.

  1. Sean F.

    Sean F. F1 Rookie

    Feb 4, 2003
    3,003
    Kansas
    Full Name:
    Sean F
    I just finished my 30k service, and the timing and carbs were set up tonight.

    It idles pretty good, but the 5-6 carb is making an intermittent spitting/ticking kind of noise. It's not constant, and only happens at idle. I drove it around the block to make sure everything was OK, an only heard the noise at idle.

    Note that the air cleaner assemble is not back on yet. It was easier to adjust things with it off.

    Also, I wished I'd know about the Exxon Valdez effect on my garage floor when the dist. are and you're setting the timing. Ugg, what a mess that was.
     
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  3. pma1010

    pma1010 F1 Rookie

    Jul 21, 2002
    2,559
    Chicago
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    Philip
    Sean
    Is it spitting back through the trumpets? Or "boiling" on top of the AC jet?
    Either sync for 5 -6 is a bit off from 7 - 8 or its lean. Richen the mixture screw by 1/4 - 1/2 turn to see if it goes away.
    Philip
     
  4. Sean F.

    Sean F. F1 Rookie

    Feb 4, 2003
    3,003
    Kansas
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    Sean F
    No, I'm pretty sure it's spitting.

    I'll richen it up and see what happens.

    I will say it's a lot better than it was. Before, it would make a cough/hickup noise whan I shut it off. Now that's gone.

    Thanks
     
  5. yelcab

    yelcab F1 World Champ
    Consultant

    Nov 29, 2001
    10,233
    San Carlos, CA
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    Mitchell Le
    I say it is a little mismatched myself. Do you have an air flow meter? Did the carbs get rebuilt?
     
  6. Sean F.

    Sean F. F1 Rookie

    Feb 4, 2003
    3,003
    Kansas
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    Sean F
    The caugh/hickup was BEFORE I did my 30K service. Last night I was setting the timings and got that OK, but the carbs need to be adjusted as well. A friend was helping me and we got them close, except for the spitting on 5-6.

    I tried to richen' it a little and it did get better, but still a random spitting out the top.

    I went for a tests drive and after everything was good and warm I ran it up to 7000rpm in 1st to see how it would do and there was definite hesitation after 7K.

    The carbs. need a rebuild I'm sure, but I don't have the cash right now.
     
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  8. yelcab

    yelcab F1 World Champ
    Consultant

    Nov 29, 2001
    10,233
    San Carlos, CA
    Full Name:
    Mitchell Le
    After I rebuilt my carbs, and set them up with a flow meter to make sure all the cylinders draw equally, and solved the needle valves problems, my carbs never spat or bucked or misbehaved at all.

    I would adjust some more but leave well enough alone until you are able to fully redo all the carbs inside out. For example, a bad float may flood one cylinder or two creating a spit. And, you can't adjust that out.
     
  9. pma1010

    pma1010 F1 Rookie

    Jul 21, 2002
    2,559
    Chicago
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    Philip
    I don't want to scare you, but check the flow of gasoline with the pump on, but without the motor turning over. A stuck float or faulty needle can cause gasoline to poor into the motor with very expensive consequences. It doesn't take much. I just rebuilt a set of carbs. On the first filling of the float bowls #7&8 kept on flooding. I took off the top cover, adjusted the float alignment very slightly, reset the float height (both) and it has been problem free.

    Allen Bishop reports of a small speck of dirt causing a needle valve to stick open...it ruined (hydra-locked) the engine. Extreme, yes. But, $200 to rebuild the carbs is a great investment (and an education if you've not done it before) versus the $$$$ involved in pulling and replacing a motor.
     
  10. Sean F.

    Sean F. F1 Rookie

    Feb 4, 2003
    3,003
    Kansas
    Full Name:
    Sean F
    The car ran fine before I did the 30k, and I did not touch the carbs, except to try and get the flows equalized. I don't think it's to serious of a problem. More of a operator error than anything.

    I think they just need to be tuned. A friend of mine who's done these before is going to help me with it. In the meantime, it will just have to sit in the garage until he can help me.
     

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