308 carb popping and banging | FerrariChat

308 carb popping and banging

Discussion in '308/328' started by snowsports1, Aug 10, 2019.

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  1. snowsports1

    snowsports1 Formula Junior

    Jan 31, 2013
    918
    UK
    Full Name:
    Brian
    #1 snowsports1, Aug 10, 2019
    Hi i am after some advice on my carb 308. It is a single distributor engine with two coils and resistors. 1977 dry sump. The car seems to start ok and tick over fine. But as soon as you press the throttle it pops and bangs from the exhaust and all the carbs. So far I have changed the distributor for a professionally rebuilt one, changed and checked plugs and gaps, checked timing, balanced carb airflows, changed fuel, carbs rebuilt. None of these items made any difference so running out of ideas.


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  2. topcarbon

    topcarbon F1 Rookie
    Silver Subscribed

    Nov 3, 2006
    2,584
    #2 topcarbon, Aug 10, 2019
    After a long exhaustive elimination process, having the same problem, turned out to be a timing issue for
    Me
     
  3. Andy 308GTB

    Andy 308GTB F1 Rookie
    Lifetime Rossa

    Jun 2, 2004
    2,627
    Essex, UK
    Full Name:
    Andy M
    #3 Andy 308GTB, Aug 10, 2019
    I'm no expert (believe me) but when I was setting my carbs up, the car only cracked and banged when it was running too lean.
    Once the carbs had been set up correctly, I subsequently got more cracking and banging when the exhaust starting letting fresh air in between the manifold and the box.

    But, as above, a timing issue is also a good shout.
     
  4. snowsports1

    snowsports1 Formula Junior

    Jan 31, 2013
    918
    UK
    Full Name:
    Brian
    #4 snowsports1, Aug 11, 2019
    I’ve set the timing as the workshop manual at 6 degrees. I had to reset the timing when I installed the new distributor but the symptoms are exactly the same. What’s confusing is the issue appears to be on all cylinders, I am going to empty the fuel tanks completely and try new fuel (again)


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  5. TonyL

    TonyL F1 Rookie

    Sep 27, 2007
    3,838
    Norfolk - UK
    Full Name:
    Tony
    #5 TonyL, Aug 11, 2019
    Brian
    Double check the leads are OK (not shorting) and connected correctly
    Tony
     
    snowsports1 likes this.
  6. 4right

    4right F1 Rookie
    Rossa Subscribed

    Sep 14, 2008
    2,907
    US/Japan/Singapore/Canada/US
    #6 4right, Aug 11, 2019
    When was the last time that the carbs were rebuilt? I had this issue in the past, after the carbs were rebuilt with new jetting, the issue went away.
     
  7. T308

    T308 Formula 3

    May 12, 2004
    1,008
    Southern Cal
    #7 T308, Aug 11, 2019
    Just had a similar problem with my 78. Was running fine for years then decided to start popping and spitting. Removed and replaced original fuel pump and filter (all kinds of sediment in the fuel bowls) , complete disassembly and rebuild of carbs and distributors. Runs like new now. After 40 years and 25 years of California gasoline it just needed a refresh.
     
  8. John B

    John B Formula 3

    May 27, 2003
    1,564
    NJ
    #8 John B, Aug 12, 2019
    I cleaned, set the float levels, re-jetted, and synced the carbs on my '79 308 according to "Birdman's" procedure and the popping stopped. US cars were set up lean to begin with to pass emissions in the day and our gas currently with 10% ethanol in it probably just makes matters worse. I went from 1.35 to 1.40 Main jets and .55 to .60 pilot jets. I ordered the jets from Pierce Manifold in CA. I also switched out the dual points ignition to a Pertronix 9MR 183 Ignitor II electronic ignition. Birdman's instructions were clear and concise and my car runs much better now.

    http://www.birdman308.com/service/floats/float_height.htm

    http://www.birdman308.com/service/sync/carb_synch_tutorial.htm
     

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