Struggling with 208GT4 ignition | FerrariChat
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Struggling with 208GT4 ignition

Discussion in '308/328' started by Pero, Jul 8, 2011.

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  1. Pero

    Pero Formula Junior

    Apr 22, 2011
    825
    Sweden
    Full Name:
    Peter R
    #1 Pero, Jul 8, 2011
    Just changed my ignition to Crane Cam. After mounting it and also adding new rotors, caps, spark plugs and wires and coils the engine refused to start. Finally I manage to get it going but really really bad. Checked static timing, 5 degeers on this model, again and again and again. Not any better.

    Removed, again, the new caps and just checked that everything was in order and that there were contact between contacts inside cap and the wire at spark plug end. No contact for cylinder 7! Unscrewed the brass screw and saw that it had not touched the copper wire, only penetrated the plastic around it. Put everything back and still not good. Checked, new, coils and the rear one was broken, no spark. So the engine had been running, or stumbling, on three cylinders! New coil today and now it starts.

    Question: the static timing is now set on 5 degrees. How do I correctly set the dynamic timing? For 208 it should read with strobe 14 at 3500 rpm and 29 at 5000. If I need to adjust it which one is the important one? If I adjust, the static will no longer be at 5 degrees. Am I missing something here?


    /Pero
     
  2. Peter

    Peter F1 Veteran
    Owner

    Dec 21, 2000
    6,441
    B.C., Canada
    #2 Peter, Jul 9, 2011
    Last edited by a moderator: Sep 7, 2017
    Both of those numbers are important. Run the engine and see if it can achieve those numbers using your timing light. If not, the distributors will have to be removed, taken apart and the advance mechanism rebuilt (usually by adding shims under the pin heads of the spring assemblies to adjust the timing sequence). If done properly, static timing will not be affected (if you are able to re-install the CraneCams trigger sensors and the distributors themselves back into their proper places).

    As for the dimensions of the parts in my photo below, yours will be different...
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  3. Pero

    Pero Formula Junior

    Apr 22, 2011
    825
    Sweden
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    Peter R
    #3 Pero, Jul 10, 2011
    Thank you Peter for taking the time to reply. I will go from there today.

    /Peter
     
  4. Sledge4.2

    Sledge4.2 F1 Rookie

    Oct 19, 2007
    4,789
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    Geno
    #4 Sledge4.2, Jul 10, 2011
    Peter, that is a very helpful post, thank you.

    Geno
     
  5. Pero

    Pero Formula Junior

    Apr 22, 2011
    825
    Sweden
    Full Name:
    Peter R
    #5 Pero, Jul 11, 2011


    Hi Peter,
    Measured the timing. Cylinders 1-4 seems nearly ok. Goes up to something like 25 degrees for 5000 rpm. Should need some extra 5-7 degrees. The 5-8 cylinders seems to go up to like 18 degree but not more. Could you give me a hint where to start on my first attempt to adjust it. To me it is like I need more movement and therefore not shims, but shorter springs instead? Since it is higher revs, the adjustment should not be on the "yellow dot", but the other weight?

    /Pero
     
  6. Peter

    Peter F1 Veteran
    Owner

    Dec 21, 2000
    6,441
    B.C., Canada
    #6 Peter, Jul 13, 2011
    Last edited by a moderator: Sep 7, 2017
    Sorry for the late reply.

    I would suggest you remove the distributors and take them apart. I am sure you will find that the pins will have large flat-spots on the ends as well as mating wear spots on the inside surface of the cup (see photos). This allows the weights to swing out immediately and therefore, you have little remaining "sprung" advance movement left (in your case, causing it to only run out to 18 degrees and no more).

    With this problem, you'll need to do the opposite - insert very thick shims or longer springs to take up the wear.

    Keep in mind I have never found a source for new, OEM Marelli advance parts, so you'll have a very difficult time finding longer springs at the same rate rating (and they are very heavy rate springs!). Your only option would be to buy small washers and use them as shims, or buy NOS Marelli distributors... :(
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  7. Pero

    Pero Formula Junior

    Apr 22, 2011
    825
    Sweden
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    Peter R
    #7 Pero, Jul 14, 2011


    Thank you Peter,
    I'll try to follow your kind advice. Tried the Superformance weights and springs but with no success. They had almost no movement, hard springs and to narrow tolerances in the parts, so they were hard to get beyond the initial five degrees. At least I have some material to work with... My knowledge of physics is not that bad, but this system is very intriguing.

    /Pero
     

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