S125 Dwell angle | FerrariChat

S125 Dwell angle

Discussion in '206/246' started by TonyL, Sep 23, 2017.

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  1. TonyL

    TonyL F1 Rookie

    Sep 27, 2007
    3,811
    Norfolk - UK
    Full Name:
    Tony
    Out of curiosity does anyone know the dwell angle for the S125 MM Distributor. 3 lobe cam twin points
     
  2. Stefan Elshout

    Stefan Elshout Karting

    Dec 1, 2011
    166
    Holland
    I think in reality it does not really matter for a Dino. The original Dinoplex Capacitive discharge ignition does not rely on dwell angle to charge the coil. Only if you would drive it on the inductive 'emergenza' coil it would matter.
     
  3. TonyL

    TonyL F1 Rookie

    Sep 27, 2007
    3,811
    Norfolk - UK
    Full Name:
    Tony
    Thanks Stefan.
    Having removed the old Black Stallion system from my car because it failed, for now I have returned the ignition system back to the original layout but with the Superformance Super 4 ignition module housed in the original MM box and the three spring points. The points have been phased and work perfectly and so does the advanced mechanism. I have measured the dwell angle at 45.2 degrees but don't have much idea if that is within the guidelines as I cannot find any data on this at all.

    Taking this (dwell) measurement now when the system is fully functional and working perfectly gives me a reference point to check and monitor points wear and adjustment easily rather than dismantling the whole system to check the points gap. A simple test of the dwell angle on a multimeter is so much quicker and more accurate in my opinion.

    Tony
     
  4. Stefan Elshout

    Stefan Elshout Karting

    Dec 1, 2011
    166
    Holland
    That's correct but the main question would be, what do you really measure if you measure dwell angle on a dual points system. For example, f you have a normal dwell angle multimeter and 1 set of points is adjusted to 30 degrees of dwell and the other set of points is adjusted to 40 degrees of dwell it will most likely show the average of 35 degrees of dwell.
    To set these distributors up correctly with the right phasing and dwell you will need a distributor testing machine, even then it is still quite some work to get them really within spec. Therefore the original CD-ignition is relatively easy to setup right because it just relies on when the points open and close and not on dwell.
     
  5. TonyL

    TonyL F1 Rookie

    Sep 27, 2007
    3,811
    Norfolk - UK
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    Tony
    Hi Stefan. The distributor was set up on a machine by a racing specialist and phased correctly, the mechanical advance was pretty close to the original curve so all good there.

    That's probably why I cannot find anything on the dwell angle, here is the data from the test machine.
     

    Attached Files:

  6. Stefan Elshout

    Stefan Elshout Karting

    Dec 1, 2011
    166
    Holland
    Ok, than I would just leave it as is because as soon as you start changing dwell (or gap) on 1 of the point the phasing changes as well. If you move 1 of the points relative to the other to change phasing the dwell changes as well.

    Normally on a 6 cylinder engine dwell would be around 2/3 so about 40 degrees... but I'm not sure if this is correct, it's just a rule of thumb.

    Attached a picture of a distributor with dual points setup that shows the phasing and dwell. You would be surprised to see that if you change the gap of 1 of the points by just a couple of hundreds of a millimeter that dwell and phasing is all of a sudden is way out of whack.
    Image Unavailable, Please Login
     
  7. TonyL

    TonyL F1 Rookie

    Sep 27, 2007
    3,811
    Norfolk - UK
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    Tony
    Thanks Stefan - My concern is the poor quality points made today and the heel wear in particular. That's why I thought about taking the dwell reading when the whole set up is in top order, then on routine servicing a simple multimeter test will tell me if that reference point has changed.

    The hot and cold starting with a correctly set up dizzy is superb, almost instant when cold.
     
  8. Stefan Elshout

    Stefan Elshout Karting

    Dec 1, 2011
    166
    Holland
    I think that is the main reason why many people switch op something electronic like the optical sensor.
    I do like points and they can work flawless but sometimes you receive sets of points from which you can only question if it is reasonable quality or crap.
     
  9. alhbln

    alhbln Formula 3
    Consultant Owner

    Mar 4, 2008
    1,749
    Berlin, Germany
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    Adrian
    True.

    Also, the Super4 is a 1:1 copy of an early seventies Bosch transistor ignition, it yields the same low output as a points and coil ignition. I would recommend to install at least a Crane XR3000 ignition or a MSD 6AL, both will suit the Dino engine much better.
     
  10. 4CamGT

    4CamGT F1 Rookie

    Jun 23, 2004
    2,649
    Southern California
    Adrian,

    Have you had a chance to test the Winterburn CD yet and compare it to the others for a points ignition?

    Freeman
     
  11. alhbln

    alhbln Formula 3
    Consultant Owner

    Mar 4, 2008
    1,749
    Berlin, Germany
    Full Name:
    Adrian
    The Winterburn CD is very similar to the original Dinoplex from a users perspective, it's quite nice both from the classic design as well as from the functionality. It would be nice if Fred would offer the core electronics as rebuild kit for broken Dinoplex units, considering that it works with an MSD Blaster II or other CDI coil and does not require the rare Dinoplex three terminal coils.

    Using points for triggering an electronic ignition requires a bit more service time for keeping the points setup up and running, especially with some of the newer productions which seem to wear down quite fast. CDI ignitions, such as Fred's, a Dinoplex or MSD unit, don't require to have a correct dwell setup so that is one less thing to worry about.
     
  12. 4CamGT

    4CamGT F1 Rookie

    Jun 23, 2004
    2,649
    Southern California
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    I've had my Winterburn CD ignition on my Dino since July 2014. I am impressed by how simple it was to install and how well it works/performs with the stock points distributor. They're reasonably priced and made with top quality electronics. Fred assembles and solders each one by hand. He's not an anonymous manufacturer. He cares about his product. By installing the correct plug, it plugs right into the stock wiring loom.

    Here's an early photo of my assembly. I've since corrected some of it per Adrian's advice.

    Freeman
     
  13. TonyL

    TonyL F1 Rookie

    Sep 27, 2007
    3,811
    Norfolk - UK
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    Tony
    This is only a temporary set up as the old BSM pdi module failed. I thought it would be nice to get it back to original for the time being and therefore refitted the old dinoplex box with the S4 inside. I refitted a new MM ballast resistor back on a Bosch coil and everything is really good and virtually as the original setup. I don't get any issues whatsoever (for now at least) but I feel the heel on the points are suspect. The guy who did the dizzy setup told me he has had lots of problems with the heel going bad on his classic racing cars so he is trying to develop his own. We shall see, in the meantime I am in no hurry to convert atm but time will tell :)
     

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