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Why does my BBi run poorly?

Discussion in 'Technical Q&A' started by garybobileff, Mar 25, 2021.

  1. garybobileff

    garybobileff Formula Junior
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    #1 garybobileff, Mar 25, 2021
    Last edited: Mar 25, 2021
    Here at Bobileff Motorcar, we had a really nice BBi come in for a timing belt change, and the owner complained that the car hesitates and isn’t smooth upon taking off. Upon inspection of the distributor, it was obvious that may have been the source of the problem, or at least contributing to the acceleration problem. In the first photo, notice a piece of the distributor advance mechanism inside the cap, as the distributor mounts horizontally. The heavy contamination was also cleaned up, and the cap showed no signs of needing replacement at that point. Once the distributor was attempted to be taken apart, the weights were so severely frozen in place, that even with heat applied, the weights could not be removed. Ultimately, the pivot pins for the weight mountings broke, so new pins need to be fabricated on the lathe, and welded into place, with new “ hats” ( the broken piece inside the distributor cap) replaced, bearings replaced, cleaned, and lubed, it’s ready for installation.

    Gary Bobileff
     

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  3. wmuno

    wmuno Karting
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    Bill Muno
    A very clear message that for vintage V-12s distributor service is more than checking the spacing of the points.
     
  4. Ak Jim

    Ak Jim F1 Veteran
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    Dec 23, 2007
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    Any thoughts on why it got so rusty?
     
  5. garybobileff

    garybobileff Formula Junior
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    Boxers develop lots of condensation on the distributors. Even so, there is a fiberglass overhead shield that is supposed to protect the distributor cap from rain and car washing, which is a good idea, but barely effective. Condensation and temperature change that drifts up from the hot exhaust headers when the motor is shut off doesn't help. It's kind of like a botanical garden inside a distributor! The rust particles comes from the advance mechanism pieces, which are made of steel, and rarely get lubricated.
    Gary Bobileff
     
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  6. 2NA

    2NA F1 World Champ
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    Too much washing, not enough driving. I've found rust in hidden areas (inside doors) on cars that have never seen rain.
     
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  8. BigTex

    BigTex Seven Time F1 World Champ
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    Thanks Gary!
     
  9. 2dinos

    2dinos F1 Rookie

    Jan 13, 2007
    2,526
    Another contributor is ozone. The environment inside the large 12cyl cap is ferocious. The 6 cyl Dino cap is slightly less aggressive followed by the 4 cyl 308 cap. That environment is similar to a plasma chamber used to clean and prepare surfaces for bonding. It makes it clean on an atomic level. Steel is extremely rust prone after this surface 'treatment'. It attacks lube and other coatings to protect rust. Best thing to do is service the distributor regularly. The Owners Manual calls for a 30,000km distrib service. IIRC, this is same for 308, so (imho) much shorter service intervals is probably a good thing.

    Also - Some lubricants have specifications on ozone. Something to consider
     
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  10. dwhite

    dwhite F1 Rookie

    I had a problem with my 84 bbi. The inside of the cap was developing verdigris on the contacts and causing very poor running. It took about 6 months to get it completely resolved as it was a combination of small issues I have since resoved.

    I did do one thing to a cheap cap and it's still on the car (atleast 6k miles), I drilled a small hole through the top to vent it and I don't run it with the suppresion surround. I drive my car alot 10,000+ miles since I acquired it in 12/13. And it does get washed, and blown dry with a leaf blower. I also put a HF $2 tarp over the engine when washing.

    Lack of use is probably the main thing which would cause a distributor to get to that condition, IMO. Sad, very sad. Such great street cars to drive and for the price of a used 488.
     
  11. ssgharkness020147

    ssgharkness020147 Formula Junior
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    Beautiful work!
     
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  13. staatsof

    staatsof Seven Time F1 World Champ
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    I went through the similar distributor on my Espada and fortunately it didn't look that bad, no evidence of moisture, though the 4 sets of point were a complete mess what with half the spring straps broken and flailing about. I went the pertronix route and built my own kit as they didn't offer one at that time. I heard all kinds of horror stories about the advance mechanism and a lack of parts. Fortunately mine HAD seen some lubrication service and the wear wasn't all that bad. When a friend put it on his distributor machine it had a reasonable advance curve. But if I had my druthers this is one function I'd also like to make electronic. I think that entails adding 4 large MSD electronic boxes.

    I'm surprised that this one ran at all ...
     
  14. raemin

    raemin Formula Junior

    Jan 16, 2007
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    This one does have a reluctor not points, so it can still generate a firing signal. The problem here is more related to the mechanical advance that for sure is completely stuck by the rusty stuff.

    With "fixed" advance, no doubt the engine had lost a few HPs at high rpms.
     
  15. staatsof

    staatsof Seven Time F1 World Champ
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    Yeah I saw that and wondered if that was stock or what? He did say BBi so I guess that figures. Espadas never got such stuff. Just ignition boxes near the end.
     
  16. raemin

    raemin Formula Junior

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    Indeed this is the original Magneti Marelli Dinolex ignition system, similar to GM HEI. This is not an hall effect sensor on the flywheel (like on modern ignition), but a star shaped reluctor (one tip per cylinder) that activate a magnetic pickup within the distributor. Unlike hall sensor systems, the electronic module does not manage advance curves, so there is still a spring mechanism that rotates the reluctor in order to increase the advance under high rpm.

    Also these are breaking the negative side of the coil, just like point ignitions whereas regular electronic ignition does break the positive side of the coil. This did require a specific coil with a negative post that is isolated from ground as the high negative voltage would damage the battery.

    So these are kind of halfway designs between points and fully electronic ignition (performance wise these are just as capable).

    it's unfortunate the distributor illustrated here was brought to such poor conditions: unlike points, these reluctor distributor are quite reliable as long as they are dry, clean and lubed. Some do advice to replace the seal as it isolates the distributor internals from the engine heat.
     
  17. JCR

    JCR F1 Veteran
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    The most reliable bang for the buck conversion is to GM HEI 4 pin module with reluctor, etc. if you are using a distributor. On a street car CD ignition is inferior to inductive. No automaker is using CD ignition.
     
  18. staatsof

    staatsof Seven Time F1 World Champ
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    The purpose of MSD boxes is to eliminate the mechanical advance mechanism and define it electronically but I don't know of anyone who's tried this. A number of Lamborghini owners have just gone full digital but I wanted my car to remain looking stock which is why I went the Pertronix route and it works great. My mechanical advance was in great shape so I left it alone.
     
  19. raemin

    raemin Formula Junior

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    The 4 pin module will never cope with the Ferrari: 12 cylinders at 6600rpm is roughly the same number of sparks than a V8 at 10.000rpm. The stock GM HEI was hardly capable of handling 5000rpm, later revisions were better, but 10.000rpm is a far stretch. So one would have to invest in a more expensive module, but they are indeed many affordable HEI after-market modules that could do the job, without any surgery in the engine bay.

    As far as the mechanical advance is concerned MSD boxes (such as 6AL or street-fire) do not provide advance curves unless you pay for the high end programmable ones. But if we go this route this also implies to swap the reluctor in favour of a hall sensor (The 412 had such an upgrade, I presume the later boxers did receive the same upgrade?). This would largely depart from the original setup and you would still be stuck with the same distributor cap.

    The point of failure is located in this cap: the previously mentioned ionisation builds up debris and rust all over the place. Be it MSD, HEI, or stock, one would still have to inspect the distributor and keep it clean & dry. While you are there, adding a few drop of oils to the advance mechanism is not such an issue. So keeping the advance mechanism seems reasonable to me.

    At the end of the day a Magneti Marelli ignition are nice performers, but they do need a minimum of care. Congrats to @garybobileff for resurecting this poor neglected one!
     
  20. JCR

    JCR F1 Veteran
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    You use one module per distributor.
     
  21. raemin

    raemin Formula Junior

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    #18 raemin, Apr 7, 2021
    Last edited: Apr 7, 2021
    On the later version, such as the one illustrated here there is a single 12 cylinder distributor, so more than 1500 sparks per seconds on a boxer at full rpm. No wonder this environment is "Ferocious". So you definitively need a beefy HEI module capable to handle such frequency (Pertronix Digital HP and MSD6 are the ones recommended on FChat).

    Older carburated engine with dual distributor are not as demanding, so you can make it do with the stock GM module, but you need to butcher the points in order to insert the reluctor, while on the BBI there is zero modification to be made on the distributor and even the stock 1.5ohm coil can be re-used. That's the reason why would keep this system as stock as possible.
     

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