Does The Colortune Really Work On A 308? | FerrariChat
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Does The Colortune Really Work On A 308?

Discussion in 'Technical Q&A' started by donaldh2o, May 12, 2005.

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  1. donaldh2o

    donaldh2o Karting

    Nov 10, 2003
    143
    Irvine CA
    Full Name:
    Don
    #1 donaldh2o, May 12, 2005
    Having trouble dialing in the carbs on my '76 308.

    I know about the Colortune - a transparent glass spark plug that lets you see the spark and allows you to adjust the fuel/air mixture to achieve the right color - but I thought it wouldnt work on a 308 because the spark plugs are so recessed.

    Has anyone ever used one on a 308?

    Also, what is the thread size on the 308 spark plugs?
     
  2. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
    36,750
    Cowboy Capitol of the World
    Full Name:
    Brian Crall
    #2 Rifledriver, May 12, 2005
    14x1.25.

    It would work on the rear bank I think but you couldn't see it on the front.

    I was loaned one of those about 25 years ago to try out and the instructions printed at that time had you making the mixtures way too rich.
     
  3. geekstreet

    geekstreet Karting

    Feb 7, 2005
    220
    Sydney
    Full Name:
    Cam
    #3 geekstreet, May 12, 2005
    Don, I would have thought that being deeply recessed would actually assist in getting a better "view" of the combustion colour, as there is less ambient light distraction to deal with. Bear in mind that deciphering the flame colour with one of these is a "learned" art, so be patient. With regard to the front bank you'd need to rig-up a mirror system I guess, shouldn't be too impossible (??)

    With regard to using one to get the right mixture, I guess what you are really after in your case is just getting a CONSISTENT result for all cylinders, whether too rich or lean. I'd first run through ALL cyls in turn without changing anything, noting down what colour you are getting. Tools like these need a lot of experience "reading" the subtle differences, so spend some time getting used to it by looking at all cyls first. Note down any differences - by the time you've gone through all 8 hopefully you have noted some which look "different". If not, either everything is perfrect or the tool is of no help!

    Now you can go back to the different cyls and start experimenting to get them closer to the others. As said, I'd first try to get them ALL looking the same before trying to set each one up to the "ideal" colour, whatever that is!

    Once the same, you can then use other methods (plug colour, changes in idle smoothness/speed, CO analysis, etc) to determine if you're overall too rich or lean.
     
  4. lusso64

    lusso64 Formula 3

    Apr 12, 2004
    1,535
    Simi Valley
    Full Name:
    David
    #4 lusso64, May 13, 2005
  5. ham308

    ham308 Formula Junior

    Nov 3, 2003
    358
    NE Switzerland
    Full Name:
    Richard Ham
    #5 ham308, May 13, 2005
    The one I bought recently had a extension tube with a mirror on top, so it worked fine even for the front bank. OK it´s no fun doing it on a hot engine but you can see the colour of the flame.

    For me with my lack of experience with a colortune, it only gave an approximate setting. Easy to see where it is too rich (yellow), but then there was a comparatively large range of the idle screw rotation that showed the right colour (blue) before it was obviously too weak.

    In the end I found putting a restriction on and off over each throat was the best method. The engine either speeds up (too weak), slows down (too rich) or does nothing (correct). The spark plugs certainly look spot on now and it idles well.

    hope this helps and best of luck
     

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