'76 low idle issue. elevation? | FerrariChat
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'76 low idle issue. elevation?

Discussion in '308/328' started by Ferraripilot, Jul 16, 2006.

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  1. Ferraripilot

    Ferraripilot F1 World Champ
    Owner Project Master

    May 10, 2006
    17,849
    Atlanta
    Full Name:
    John!
    #1 Ferraripilot, Jul 16, 2006
    Hey everyone, I am just getting to know this thing and so far, I am very pleased. The car spent it's entire life in Marin county which is for the most part, at sea level. The car is now at a higher elevation of 2100 feet as well as a much drier climate. I am trying to figure out why the car is idling at 600-650. No matter the engine temp, it idles at 600-650. The car has slight backfires on decel, though I am not too concerned with this issue. There is by the way, the occasional light backfire after the car shuts down. Is the car too rich or too lean. The plugs look okay and I have already replaced them with the same idling results. The carbs were rebuilt within 4k miles along with the belts. Does this sound like a cam belt jumped a tooth or could this be a pure elevation issue. Thanks in advance! -john
     
  2. Perfusion

    Perfusion F1 Rookie

    Oct 16, 2004
    4,151
    Marietta, GA
    Full Name:
    Aaron
    #2 Perfusion, Jul 16, 2006
    My car behaves similarly... It is still tuned as it was by the previous owner to pass CA Smog before the sale, so it's set lean. It idles rather low (500-600) when cold, and I just correct that with a little application of right-foot. When fully warmed up, it seems to idle a couple hundred RPM higher...approx. where it "should" be according to what I've read over the months here.
     
  3. Ferraripilot

    Ferraripilot F1 World Champ
    Owner Project Master

    May 10, 2006
    17,849
    Atlanta
    Full Name:
    John!
    #3 Ferraripilot, Jul 16, 2006
    my car is strange, it idles at 600-650 cold, then about 550-600 when hot. If the car is hot enough, it will stop running all together if your foot is off the accelerator. Sounds like it is running rich to me. I am thinking I should turn all the screws in on the idle adjustement 1/3 of a turn to see what that does. The car has been synced every year by the same guy since new in CA but, I can't exactly get the car out to him just to do that so I am left with myself here. Am I thinking in the right direction here?
     
  4. thecarreaper

    thecarreaper F1 World Champ
    Silver Subscribed

    Sep 30, 2003
    18,066
    Savannah
    #4 thecarreaper, Jul 16, 2006
    the air is thinner and its tuned for sea level. so it would be a bit rich. the pop after shut off is an indication of unburned fuel igniting in the exhaust. my 308s only did this when they were not tuned properly. i would check your jets and see whats in there before messing with the sync or carb linkage. i would run 135 /55 main and idle jets ( rich) at sea level) with a 200 air corrector and F36 emulsion tube.
    i would try 125/55 at your altitude. you should be able to raise the idle without messing up the carbs sync. there are threads by Birdman with great pics as to what screw does what job. Piece Manifiolds has all of the carb parts you need and i would get a Syncrometer also. they are very helpful. having 2 of them for bank to bank comparsions are even better.

    rich is always better than lean. lean conditions burn valves and pistons, and with the cars getting up in years with sodium filled valves, that could get VERY expensive if there is a failure!

    best


    :)
     
  5. Birdman

    Birdman F1 Veteran

    Jun 20, 2003
    6,689
    North shore, MA
    Full Name:
    THE Birdman
    #5 Birdman, Jul 16, 2006
    Don't just tweak idle screws! Get a synchrometer and do it right, matching flows. Read here:

    www.birdmanferrari.com

    Birdman
     

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