308 GT4 twin distributors timming, elec timming and carbs adjusting | FerrariChat
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308 GT4 twin distributors timming, elec timming and carbs adjusting

Discussion in 'Technical Q&A' started by Fave, Aug 14, 2010.

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  1. Fave

    Fave F1 Rookie

    Aug 12, 2010
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    L. Ike Hunt
    #1 Fave, Aug 14, 2010
    Hey I'm trying to figure a couple things out here.
    I have the GT4 with twin distributors, the previous owner removed the wires that conect the accelorator pedal switch to the second set of points, from what I understand it effectively leaves the points shut off so at idle they won't work.

    1st question, should I put this wire back on? I know it sounds stupid but he felt it was a redundant system more for environmental reasons than anything. Regardless I'm sure it should be on there.

    2nd timing, I have a workshop manual but not for the twin distributors and I would like to read up on setting the timming as the previous owner said his mechanic set the timing to 0 degrees TDC, which I have no idea how this car would be running as well as it does set to this. It's a bit rough and it spurts a bit at idle and low rpm, but I'm assuming that has more to do with the above issue not having the 2nd points hooked up.
    So I'm wondering if there is someplace I can find this info on setting the timming.

    3rd, what are the thoughts on removing the points and going electronic? I know purists may barf, and I am one mostly, but I don't relish the thought of playing with the points if I dont have to. Who makes them and how well do they work?

    4th and lastly, carbs. I have a weber book, I want to read up on adjusting these from the Ferrari perspective, so same as the second question is there a place I can find more info on adjusting these carbs?

    Thanks
     
  2. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #2 Steve Magnusson, Aug 14, 2010
    Last edited: Aug 15, 2010
    Save this copy of the 308GT4 WSM for yourself:

    http://ferrari.cdyn.com/ferrari_docs/308gt4_workshop.pdf

    Section L describes the twin distributors system with R1 and R2 points for 308 using the S159A distributors. Section O describes the twin distributor system with R1 and R2 points for 308 using the S159B distributors. At idle, the throttle microswitch is closed -- this causes the each coil to not fire when its corresponding R1 points open, but only later when its corresponding R2 points open (3 deg ATDC for S159B distributors). When the throttle is opened, the throttle microswitch is open, causing each coil to to fire when its corresponding R1 points open (7 deg BTDC for S159B distributors) and the R2 points are inactive.
     
  3. thecarreaper

    thecarreaper F1 World Champ
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    Sep 30, 2003
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    #3 thecarreaper, Aug 15, 2010

    i have had several carb ferraris, and usually put an optical / electronic ignition in, as i detest points. Pertronix makes a new ignition system, there was a recent thread about it, its drop in, and very good. i used Crane x700 and xr 800 ignitions in the past, not sure you can still get them though.

    dcnf 400 308 carbs i ran55 idle /125 main / 200 a/c for the initial set up with NGK plugs in the 6 heat range.

    i would not mess with more than one thing at a time.

    also, get two syncrometers from Ricambi, syncing the carbs is critical to how the car behaves, and after a few tries you will be amazed how much you can learn about how the car is running but the sound, smell and feel of it.
     
  4. duck.co.za

    duck.co.za Formula 3

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    #4 duck.co.za, Aug 15, 2010
    Take a look at Birdman's site he has a great write up on synchronising the carbs and other great reads
    www.birdmanferrari.com
     
  5. Fave

    Fave F1 Rookie

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    #5 Fave, Aug 15, 2010
    Thanks guys,
    I have learnt allot about this stuff from my wwII era bike. Concept is all the same so I'm pretty familiar with most of it. But this twin distributor thing and double points has gotten me a bit confused.
    Quick question, if you are using a dwell gauge for the point gaps is it considered a 4 cylinder because 4 are on one distributor? Or 8 cylinders.
     
  6. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #6 Steve Magnusson, Aug 15, 2010
    Use the 4 cylinder scale/setting on the dwell meter (because 4 are on one distributor).
     
  7. Fave

    Fave F1 Rookie

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    #7 Fave, Aug 15, 2010
    I thought as much, cheers
     

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