Bora: CD ignition box & coil 1973 US 4.9 | FerrariChat
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Bora: CD ignition box & coil 1973 US 4.9

Discussion in 'Maserati' started by highwaybora, Oct 22, 2014.

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  1. highwaybora

    highwaybora Karting

    Jun 18, 2013
    150
    SoCal
    #1 highwaybora, Oct 22, 2014
    My search didn't yield anything, so asking again (knowing this must have been discussed a lot): in driving, it seems there's ignition miss (pretty clearly) so
    1. what is best way to MEASURE objective voltage etc. at the plugs whilst running?
    2. if the (original) CD box needs replacement, what is best? Perma-Tune? MIE nos?
    3. What of the Coil, same age likely, probably should test/replace etc. also, to match. I understood that CD system coils have less resistance than normal 12v systems and should be 'paired'/matched to the CD box.

    Speaking of objective information, after the measurement/assessment/fix/replacement of the ignition components, as needed, then:
    -- compression test (get best info' possible)
    -- leak-down test

    I want numbers, not guesses whenever possible, to benchmark and for future reference back.

    finally, when all else known:
    -- tune /re-jet the Webers (running a bit rich post-install of new exhaust headers/system)
    -- determine any/all other parameters to then adjust/update/replace/other...

    I'd appreciate references to best known & detailed prior articles, or means to get better responses to search inputs. All good and detailed info' welcome.
    -- Best regards,
    Ned Evans
    US Bora, 1973 4.9ltr
     
  2. 71Satisfaction

    71Satisfaction Formula 3

    Jul 15, 2012
    1,312
    New York and Norway
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    Art
    #2 71Satisfaction, Oct 22, 2014
    I apologize for not knowing your level of expertise. Basics first. How do you distinguish between an ignition miss and a lean/rich mixture miss?

    If you aren't sure, start with the assumption that the simpler to check, and more common, "mixture" is the reason for misfires. The Webers will give you misses in both too lean and too rich condition. Start there unless you have "ruled them out" (and don't forget they only stay in tune until the next change in humidity, barometric pressure, temperature, etc, etc, LOL - fun stuff DAMHIK).

    (I acknowledge the above is not the comprehensive, searchable, ignition spec database you requested)
    Best,
    - Art

    PS - Scroll down the forum threads to 09-26-2014 for a detailed discussion and step-by-step procedure for Weber adjustments.
     
  3. GLB

    GLB Formula Junior

    Oct 27, 2010
    311
    Dallas, TX
    Full Name:
    George Lawrence Brantingham
    #3 GLB, Oct 22, 2014
  4. staatsof

    staatsof Nine Time F1 World Champ
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    Mar 13, 2005
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    Bob
    #4 staatsof, Oct 23, 2014
    I don't have the same ignition system on my Bora so I don't have any specific info on your box. But over the years fellow Maserati GT guys with these systems have had new guts put into those old boxes. There's someone out there who does this (not cheap).

    The other thing is perhaps you want to get rid of the points at this time? Before you do that though it's probably not a bad idea to have the health of your distributor checked out. I think yours is also a Bosch?

    You also have the switch to cut the Bosch box out if it fails right? Have you tried that?

    And thank the stars it's not a Marelli! If you suspect the advance mechanism is at all faulty then have it overhauled and also get the points converted to something else.

    See if Pertronix has a kit for that dizzy. It may? work with your existing CD box. Ask them. Pertronix kits are basically undetectable from a visual standpoint and they work great. I have them on my Espada and no CD boxes at all though they do work with MSD stuff.

    You're also asking a whole lot of stuff all at once.

    I had a real SOB ignition for several years on my Bora and I had a devil of a time finding a shop with the proper diagnostic equipment and qualified technician to figure it out. I never did find one for that and it took me a lot of years and money to discover that my wiring harness for the magnetic trigger in the Bosch distributor had a twist in the harness color code wise from the factory that had been compensated for as it entered the Bosch box before it left the factory. When I restored the entire harness I followed the color coding and inadvertently removed that compensation. What a SOB that was.

    Don't be me. Spend some money at a very qualified, cooperative garage that will also let you learn something from them. I wish I could have found someone like that at the time because it would have saved me a lot. It's a whole lot easier to find people like that now than it was in in the early 1990s. I think a good tech could have detected what was wrong with my car a whole lot sooner.

    I chased carburetion and ignition issues for a long time on that one and it was just a pair of wires ...

     
  5. doublegarage

    doublegarage Rookie

    Aug 8, 2009
    21
    #5 doublegarage, Oct 25, 2014
    To try to answer your questions:
    1) "what is best way to MEASURE objective voltage etc. at the plugs whilst running?"
    I don't know of any way to do it - we're talking about 30-40kV. It'd be best to have a known good coil with known parameters and measure the voltage at the primary (points) side and then calculate the voltage at the secondary (plug) side.

    2) The MSD ignition you mention is a good example of a modern CD ignition, with the added benefit of multi-spark ignition at low-revs for a more complete burn. Then you need to get a "points-replacement" pickup. On my Ghibli I have an optical pickup (Lumenition) driving an MSD setup - works great. Crane XR-700 is a good system. Many people swear my Pertronix, I have a 4-cyl car on which it works well but I don't like that they claim it's a "Hall Effect" transducer when in fact it's just a cheap magnet.

    3) Coil - whatever you choose above you have to get a coil to match the ignition you pick - don't try to use a CD coil with transistorized ignition. Cheap insurance.

    As someone mentions above, you should always be suspicious of the state of your distributor's advance mechanism after 40 years. That could definitely be a cause of misfiring. Remove the distributor and take it to someone who can run it on a distributor machine and plot the advance curve, maybe fix it if it's bad. Some know-how is required here...it's all little springs and worn pivots and flopping weights. I recently fixed a Marelli Dino distributor that had at least 4 things badly wrong mechanically with it (although a Dino distributor has a harder life than the 4.7 V8 unit, and it's not a Bosch)

    On the Ghibli the ignition was borrowed/shared from the Mercedes 6.3L V8 cars - so any modern improvements for that car translate well to the Ghibli - sorry I don't know whether that's also true for the Bora.

    -Richard
     
  6. highwaybora

    highwaybora Karting

    Jun 18, 2013
    150
    SoCal
    #6 highwaybora, Oct 27, 2014
    Good responses. Sorry to have perhaps brought up too much at once, but it's what's on the plate for now. I appreciate all the information and sharing below, and can sort out some now accordingly:

    Art--thanks for your added experience and references regarding the Webers, which I had read (and kept) from before. I'd started thinking I'd do all that, and then the more I drove it (and had experienced mechanic, race driver, and friend do so) the more it became clear that the sharpness and nature of the miss/s was ignition break-up. Carb's will have to wait.
    PS.. My experiences with hands-on as to the Bora are much more limited than days of yore long past when I did engine transplant etc. on domestic iron. Somehow I'm not as hands-on with the funny furrin' cars. I do have a local excellent one-man show mechanic expert, well known and respected. And (no 'waiting room', staff, etc.) I can talk directly with him and he makes sense. I'll add more by following separate message (next).
    Ned.
     
  7. highwaybora

    highwaybora Karting

    Jun 18, 2013
    150
    SoCal
    #7 highwaybora, Oct 27, 2014
    Cont'd. Thanks 'GLB' for article reference. Pelican is a good resource generally, and I'll go through this article several times, then let you know what seems to apply.
    "PermaTune" is a well-known name for Bosch box replacements, and I'm in touch with them, on topic of this, as they know Bora previously, they say. Actually, PT was one of the first to make these boxes, and the story may be that Bosch knocked THEM off, lawsuit, etc. PT says they will insert their circuits inside my old box, undetectable from outside, connects identically, etc. I'm still not quite certain regarding matching coil but seems best to do both.
    --and, Thanks Bob S. as ever: I appreciate your full response and extensive experience, etc. You mentioned "Pertronix" and others have been mentioned also. Anyone have a comparo' reference for which of such boxes best for what cars/applications etc.? Clearly I have to surround all this. Switch adjacent to coil on my Bora is present but I never had used it... will now (good doublecheck). Actually there's two such switches, the other for an alternative fuel pump. Hm. I have the right mech'-guy I think, but he no longer has that big ol' SUN ignition diagnostic machine--it 'aged out'. Sun Distributor machine would be good to apply, and will advise if/when I find that shop and use same. Plugs and plugwires all new, and cap/rotor 'looked' good when doing that install. I would just 'on spec' replace guts of the box and a new coil, but that can be an expensive approach generally and this time I wanted to just be certain it actually was the cause of this 'missing' first. Once ignition solved, then seemed logical to measure all re cylinder pressures, valves, leak-down, etc., getting number read-outs, and THEN go for carbs' tune.
    <more>
     
  8. highwaybora

    highwaybora Karting

    Jun 18, 2013
    150
    SoCal
    #8 highwaybora, Oct 27, 2014
    Cont'd: Thanks also to Richard /DoubleGarage (below). I'll pursue your tips, and let me know if you hear more re PermaTune or the other boxes, now that it's come up (again).
    At my mech's garage (Greg) there was a newly re-roaded '73 Dino that was having ignition issues, and I got to study that setup a bit. Two coils and a switch, but seemed as though it were one of each kind of coil, depending on what box/path circuit was operational, CD vs. normal. Your mention of the need for fully healthy distributor is not taken lightly, and I'll pursue that. Going to crank-driven ignition probably overkill for a Bora.

    Thanks to all for taking the time and sharing the knowledge and experience.
    I will get back with any results/breakthroughs/progress, etc.
    Best regards and fine roads ahead,
    Ned Evans.
     
  9. staatsof

    staatsof Nine Time F1 World Champ
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    Bob
    #9 staatsof, Oct 28, 2014
    I never had an issue with the system as used on the later Boras, Khamsins and QPIIIs.

    Besides that whole thing with the wiring loom twist!:mad:

    I think the market has changed a bit but it used to be the case that you could pick some of these bits up off a QPIII parts car quite reasonably.
     

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