308 carb strange exhaust sound | FerrariChat

308 carb strange exhaust sound

Discussion in '308/328' started by Daniel France, Nov 12, 2021.

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  1. Daniel France

    Daniel France Rookie

    Oct 1, 2020
    4
    France
    Full Name:
    Daniel Gossez
    Dear members,

    has anybody ever heard those sounds?

    They appear during descent, throttle up, ending often with backfire.
    Top engine has just been renewed, advance, cam clearance and carb setting are supposed to be correctly tuned. At a first glance, exhaust doesn't seem to present any leak.

    Thanks for your suggestions.
     

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  2. morcal

    morcal Formula Junior
    Silver Subscribed

    Mar 7, 2003
    389
    Turin,Italy
    Full Name:
    Cal
    Spitting due to lean fuel mixture?
     
  3. tuttebenne

    tuttebenne F1 Rookie

    Mar 26, 2003
    3,218
    Bay Shore, NY
    Full Name:
    Andy
    Its very hard to hear what you are talking about. Are you sure the sound is coming from the exhaust and not the intake?
     
  4. Daniel France

    Daniel France Rookie

    Oct 1, 2020
    4
    France
    Full Name:
    Daniel Gossez
    I’m rather positive about the exhaust. Noise is much more important on driver side (single exhaust side) than on passenger side (intake).

    lean fuel mixture could be the issue. I noticed that with the choke on, almost no more noise, and no more backfiring.

    I’ll keep you advised.
    Thanks
    Dan
     
    absostone and lm2504me like this.
  5. morcal

    morcal Formula Junior
    Silver Subscribed

    Mar 7, 2003
    389
    Turin,Italy
    Full Name:
    Cal
    @ Daniel France: without air filter and just warming up the engine ( be careful, backfire danger! ) you may see the actual "spitting" from the single air trumpets
     
    absostone likes this.
  6. tuttebenne

    tuttebenne F1 Rookie

    Mar 26, 2003
    3,218
    Bay Shore, NY
    Full Name:
    Andy
    I tend to agree with Morcal. A lean mixture usually shows itself as pops through the intake trumpets.
     
    absostone likes this.
  7. Daniel France

    Daniel France Rookie

    Oct 1, 2020
    4
    France
    Full Name:
    Daniel Gossez
    the thing is that it’s impossible to replay the trouble if the engine is not at high rpm with throttle up, like during a steep descent
     

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