Bosch ignition for S159 double distributor setups | FerrariChat

Bosch ignition for S159 double distributor setups

Discussion in '308/328' started by alhbln, Jul 8, 2014.

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  1. alhbln

    alhbln Formula 3
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    Mar 4, 2008
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    Adrian
    #1 alhbln, Jul 8, 2014
    Last edited by a moderator: Sep 7, 2017
    Early 308 GT4/GTB/GTS cars with a double S159 distributor ignition setup are difficult to maintain as wear and age changes the advance curve of each distributor individually, e.g. both banks run with a slightly different advance which reduces a bit of power and smoothness of the engine.

    To fix this i did an installation of a Pertronix MR-183 setup with two pickups in one distributor (the second distributor just distributes the spark in such a setup), as a result the advance curve for both banks is controlled by just one advance curve.
    The engine ran a lot better but still not as smoothly as expected, so i benchmarked the S159 Pertronix setup on a distributor tester and found out that the difference in advance between the cylinders was up to 4-5º. Bought another unit but had similar results, apparently the position of the magnets in the sleeve is not precise enough to yield better results.

    After that i decided to adapt the Bosch high performance ignition setup i did for the Dino 246 some years ago, this setup uses a Lumenition Optronics OS50 optical pickup and a Bosch 0227100137 high power ignition module combined with the matching Bosch 0221122334 coil.

    For the S159 setup, a full setup is required for each bank and both Lumenition pickups are installed in one distributor (i opted for the front one). The Lumenition #262 chopper wheel required for the optical pickup fits nicely on the S159 cam after a bit of sanding. The first Lumenition pickup has been installed in the position for the front bank (0º), the second one for the rear bank is installed at 135º (a multiple of 45º) starting from the first pickup, so with the #262 four cylinder chopper wheel each pickup serves one bank.

    Testing the converted S159 distributor on the distributor tester yielded a cylinder difference of less than 1º :) The engine ran very smooth after the installation and hot and cold starts were much easier compared with the old points setup. I also installed a fresh set of NGK BPR8EIX for best results.

    This setup has a similar approach and precision as the very effective Marelli AEI200/Magnetic pickup setup in late GT4/GTB/GTS cars, but delivers 33% more power due to the higher coil current (and 100% more power compared to the factory points setup). It's a bit of work machining the adapter plate and wiring up the parts but it's quite worth the time from my experience. Also it looks quite original.

    See below for pictures and the wiring diagram of the new ignition setup.
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  2. Ferraripilot

    Ferraripilot F1 World Champ
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    May 10, 2006
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    This is brilliant! Wonderful job Adrian.
     
  3. tomberlin

    tomberlin Formula Junior
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    #3 tomberlin, Jul 8, 2014
    Last edited: Jul 8, 2014
    Looks good- having access to a distributor machine is a definite plus.
    Was adapting the Petronix base plate not a practical option?
    Also, are the power stages out of something common? (answered my own question-1987 Saab 900, amongst others I suspect)

    Cheers,
    Tom
     
  4. scowman

    scowman Formula 3

    Mar 25, 2014
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    Stu Boogie
    I was thinking the same thing.

    I remember reading an early pertronix thread where people were making their own dual trigger setups and someone made one of the triggers in slotted groves to adjust for the very problem you are trying to solve.

    Wouldn't it just be easier to do that? Maybe Fchat could get pertronix to build it that way. From the early pertronix threads it looks like Fchat got them to build the dual pickup model when they were just offering single pickups.

    Not to take anything away from you but in terms of work load for a home mechanic, your solutions looks like a lot more than a simple mod to the pertronix.
     
  5. alhbln

    alhbln Formula 3
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    The Pertronix base plate has different positions for the pickup screw posts so decided to start fresh and design a custom one.

    The power stages have indeed been used for the Saab as you posted, as well as for a range of other cars (Audi Quattro and 200 Turbo, Volvo, VW) so they are easily available as spare. They are inexpensive, deliver up to 8 ampere to the coil (resulting in a nice long spark), have an electronic dwell management and automatically switch off if there are no incoming pulses, so no overheating of the coil as with the Ignitor I or points.

    I fully agree, the Pertronix setup is much easier to install than the setup above (and half the price) but if you have to design a better magnetic sleeve to get the timing variance down to 1-2º it gets a bit tedious again. With the magnetic sensor design used in the Ignitor you have to fabricate a sleeve where the distance of the magnets to each other and to the pickup is within the fraction of a millimeter, so that might be difficult to achieve. In that perspective, an optical IR switch with a chopper wheel is a simpler to manufacture and more precise approach.

    I wouldn't mind if a shop or manufacturer would adopt the design shown above and manufacture ready to install and prewired conversion sets, then it's really plug&play and you don't need access to a distributor tester. With the amount of double dist points based 308's there might be a market for this i guess.
     
  6. GT4 Joe

    GT4 Joe Formula Junior

    Oct 19, 2010
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    This setup looks fantastic, however I disagree with your statement above.
    After testing my dizzys on a machine, I found that they both advanced EXACTLY the same. The problem is the points and the dwell changes from age/miles which then changes the ignition timing, not the advance curve for a specific RPM.
    So your single source of firing would definitely be an advantage to keep the two banks sync'd, and then of course, smoothness and HP is maintained.
    Keep up the good work!
     
  7. alhbln

    alhbln Formula 3
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    #7 alhbln, Jul 9, 2014
    Last edited by a moderator: Sep 7, 2017
    True, it all depends on the condition of your S159 distributors, if they are in very good shape (how many are? :) they should align well, but i was looking for a difference of not more than 1-2º. Points are also a factor as you said. See below how my distributors looked like after i bought my (otherwise well cared) GT4, the engine was feeling gritty at higher RPMs and was not very smooth when revving up so the first thing i did was to check out the advance curves on the distributor tester, with the curves shown below it's no wonder the engine was unhappy. All fixed now :)
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  8. jgmblair

    jgmblair Formula Junior
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    May 27, 2010
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    Hello Alhbin, old Thread but wondering if this is still something you would recommend as an upgrade? Most threads I have come across are from the late 2000's wondering if there been other off the shelf products developed recently to address the dual distributor setup while maintaining the OEM look in the engine bay? Cheers.
     
  9. alhbln

    alhbln Formula 3
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    I'm running the Bosch conversion now since 6+ years without any issues and are still very happy about the conversion. It lifts up the engine idling/running/high RPM performance up to the later single distributor engines with the single distributor and factory installed electronic ignition, and proved to be very reliable. The conversion has now been installed in a range of other double distributor 308 GT4s and GTS/GTB, with excellent results.
    I'm not aware of factory ignitions which maintain the OEM look as well unfortunately, with the exception of a Pertronix Ignitor conversion which i don't recommend due to the variance in the timing due to the magnetic ring approach.
     
  10. Luis A.

    Luis A. Karting

    Jul 14, 2010
    97
    Milwaukee, WI
    I have installed this ignition on my dual distributor Espada and can attest to how well it works, as well simplifying things by controlling all timing from one of the two distributors. I own a Sun machine and was able to “tame the beast” before I did this conversion running timing from both distributors but this greatly simplifies the upkeep. Plus, it looked completely stock having concealed the amplifiers, painted the Bosch coils to resemble the Marelli and retained the square red Marelli ballast resistors.

    Adrian I have a question for you. It is impossible for me to find the Lumenition chopper wheel by the part number you provide, #262. Seems they are sold in complete conversion kits with part numbers such as FK001, FK117, FK639 for specific cars. Do you know which kit(s) contain the #262 rotor/chopper wheel? Or where to buy the chopper wheel by itself? Thank you!
     
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  11. alhbln

    alhbln Formula 3
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    Luis, you should be able to order fitting Kits as well as single choppers directly from Autocar in the UK: [email protected]
    An alternative approach is to have a workshop produce a custom chopper wheel by CNC milling an aluminium plate for press fitting and painting it black.
     
  12. Luis A.

    Luis A. Karting

    Jul 14, 2010
    97
    Milwaukee, WI
    Thanks Adrian, I did see Autocar Electrical in my search. Stephan produced a nice CNC chopper wheel which is the one I used in the Espada but since I have no CNC know-how whatsoever I wanted to secure a commercial source for future reference.
     

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