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Quattroporte III catch-all thread

Discussion in 'Maserati' started by Quattroporte3, Jun 27, 2011.

  1. Mexico074

    Mexico074 Formula 3

    Aug 14, 2008
    1,132
    Harriman, TN USA
    Full Name:
    Michael Demyanovich
    Hello Peter...

    From one 1982 QPIII owner to another - Very Nice Work!!!!

    I always thought that there was NOTHING magical about those black boxes.
    In fact, some of them are down right simple inside..

    Please continue to keep us informed on what you find and solutions!

    Did you ever post pics of your car? I can't remember (first its the black boxes that go, then its the mind! :) )

    Mike
     
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  3. jamespeter26

    jamespeter26 Karting

    May 9, 2019
    54
    Rome, Italy
    Full Name:
    Peter
    I didn't yet start posting photos of my car but I probably should!

    I'm attaching below a picture of the electric mod I described in my previous post.
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    I've also posted two pictures of what's inside that Tedel 103 black box on the dedicated thread, for those who would be interested : https://www.ferrarichat.com/forum/posts/146905092/

    Other works I've done on it so far:
    - bare metal repaint in original Blu Sera Metallizzato (many thanks to those who posted the paint color codes)
    - new tires: Michelin XWX 225/70 R15
    - new automatic antenna with FM/DAB splitter (to avoid sticking those horrendous glass DAB antennas on my windscreen)
    - new autoradio: Blaupunkt Bremen SQR 46 DAB (period-correct look with Bluetooth, USB, AUX in and DAB radio)
    - new battery: Odyssey PC 1500-34R - great improvement which I highly recommend, I confirm that this model fits in the battery compartment of a QP III, and that's the highest/best specs I could find within the correct dimensions for this car
    - A/C conversion to R134a - fortunately, my compressor was still functional so A/C now works very well
    - new ignition leads (cavis) and new spark plugs
    - carbs cleaning, rebuild and syncing by a professional carburettor specialist (see pictures below)
    - grease the electric windows motors & mechanism to avoid premature failure
    - realign two sagging doors which caused a lot of air noise when driving above 100 km/h

    Pending works scheduled for the coming weeks/months:
    - replace the starter motor with the RobbMC mini-starter - my original starter is still working so I'll save it as spare but I know that's a common failure point so would rather anticipate (I've already received the new starter but both my mechanic and myself are quite busy these days so will do that when we have a moment)
    - reconnect the vacuometer gauge - any advice on that would be highly appreciated, I'm still trying to track down the vacuum hose and find where to reconnect it
    - reconnect or repair the centralized locking switch in the driver's door - interestingly, turning the key in the passenger side door lock (or pushing the button next to the steering wheel) will activate the centralized locking system and open/close all 4 doors, but the driver side lock seems somehow disconnected or dysfunctional and therefore I can only open/close that door when using the key
    - I'm certainly forgetting a few other things

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  4. thecarnut

    thecarnut F1 Rookie
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    Apr 22, 2006
    2,565
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    The Car Nut
    I need a copy of the QP3 Use and Maintenance manual in PDF format.

    Ivan
     
  5. thecarnut

    thecarnut F1 Rookie
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    Apr 22, 2006
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    The Car Nut
    Disregard .... I found it.

    Ivan
     
  6. jamespeter26

    jamespeter26 Karting

    May 9, 2019
    54
    Rome, Italy
    Full Name:
    Peter
    Hi guys,

    I am working on my carburetors and I feel like I could use some knowledgeable advice here.

    Here is some background: as part of the due diligence before working on carbs, I wanted to ensure that there was no vacuum leak around the intake manifold. My "consumption" gauge, in the instruments cluster, doesn't work (it basically look like it's disconnected). I haven't yet removed the instruments cluster to look if the vacuum hose is connected to it (that's something I plan on doing soon) but after looking under the hood, I found a few interesting things that don't seem normal.

    Based on earlier posts in this thread, I understand that the vacuum hose that goes to the "consumption" gauge is connected to a T splitter, which connects to two vacuum hoses directly plugged on the intake manifold - one in the rear, one in the front, forming a loop.

    Now, in my car, I see this tee and one vacuum hose going from the tee to the rear of the intake manifold. However, the second vacuum hose is not connected to the manifold, but instead, it goes to the air pump (am I correct to locate the air pump next to the expansion tank, above the A/C compressor?). There is also a short hose connecting the front of the intake manifold with a larger, black line, which I identify as the "filter hose conveyer" (n° 8 on the below schematic) - see photos (that hose is nicely cracked, by the way).

    On top of that, the air pump belt is absent from the car! The belt indicated as D on the below schematic is simply not present. And the air pump looks a bit rusted, like it hasn't been used in a while.

    Any ideas?

    On my side I have a few questions:
    - should I reconnect the second hose to the front of the intake manifold? In that case, what should I connect to the "filter hose conveyer"?
    - what can I do with the air pump? I'm not sure I can just put a belt and let it go - there must be a reason why it was disconnected from the system in the first place.


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  8. jamespeter26

    jamespeter26 Karting

    May 9, 2019
    54
    Rome, Italy
    Full Name:
    Peter
  9. Mexico074

    Mexico074 Formula 3

    Aug 14, 2008
    1,132
    Harriman, TN USA
    Full Name:
    Michael Demyanovich
    Hello Peter...

    Not sure any of this will be of use, but thought I would post it just in case...

    Below are the emissions layout plate that was on my 1982 QPIII along with some info
    on the air pump system. Not necessarily on QPIII's, but I have heard of these air pumps seizing
    which could cause who-knows-what kind of problems. If tailpipe emissions are not a concern
    where you live, such as emissions/exhaust testing, it may have been disconnected as it can rob
    some HP.. I am not saying you should or should not fully disconnect or put in back in service,
    this is up to you.

    As soon as I get a chance I will see what I have in my notes regarding
    vacuum...

    Mike


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  10. Mexico074

    Mexico074 Formula 3

    Aug 14, 2008
    1,132
    Harriman, TN USA
    Full Name:
    Michael Demyanovich
    Hello again Peter...

    Regarding the vacuum system.. I am sure you are aware the QPIII (at least the 1982 US version) has a seperate
    vacuum pump. I don't think this is shown in the parts manuals anywhere, but I could be wrong. I remember seeing references
    to it in the Service manual. Attached are two pictures showing its location on the passenger side head, and on the
    work bench. I am not sure if this pump services just the brake booster, or the brake booster and any ancilliary
    equipment using vacuum... Hope this helps...

    Mike
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  11. jamespeter26

    jamespeter26 Karting

    May 9, 2019
    54
    Rome, Italy
    Full Name:
    Peter
    Thank you Mike, that's very useful!

    I had never heard of that vacuum pump before, but your photos elicited my curiosity. I think it's in the parts manual under part no. 420.00.68.00 (nb 89 of table 22). Granted, the schematic drawing is tiny and doesn't help ascertain that it's the same part, but there's one currently for sale on eBay and the part looks similar to the one on your photos. It's called "Brake booster assy" or "Depressore completo" (Italian for "complete vacuum pump") but that doesn't tell us whether it's only used for the brakes or more.

    My car is a Euro-spec one so the emissions system isn't as elaborate as the US version, but this may explain why the air pump was disconnected in the first place. For the moment I'm not so much concerned about emissions but my mechanic recently measured 5.5% CO at the exhaust pipe and the legal threshold for older cars where I live is 4.5%... My next visit isn't until 2023 so I have a bit of time before having to worry about emissions control. However, I'm after vacuum leaks around the intake manifold as this will definitely be an issue when tuning the carbs.

    I think reconnecting the second hose coming from the tee (currently plugged on the disabled air pump) onto the front of the intake manifold shouldn't be a problem, but I'm wondering what I should plug into the "filter hose conveyer" after that. My own photos are a bit dark but here's another picture I found on Thor's blog where this "filter hose conveyer" is more visible. But we can't tell where the other end of that hose is plugged. How does it look on your car?

    I noticed some smoke/fumes coming out of the hole that is above the "filter hose conveyer", which makes me think this is the "special vacuum pipe" mentioned on page 104 of the owner's manual: "The toxic vapours inside the engine are sucked by a special vacuum pipe and finally burned by the engine itself. This pipe is provided with a wire gauze for flame extinction."

    The small hose (red arrow) connected to the "filter hose conveyer" (large vertical hose leading into the air filter box) on Thor's former QP3:
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    Pictures of the vacuum pump 420.00.68.00 from eBay:
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  13. Mexico074

    Mexico074 Formula 3

    Aug 14, 2008
    1,132
    Harriman, TN USA
    Full Name:
    Michael Demyanovich
    Hi Peter...

    The pictures and diagrams I sent aren't necessarily the most helpful to your issue, but they may assist in eliminating some
    hoses/connections. Does the diagram on Table 24 of the 'Summary of Modification to Spare Parts Catalogue 1982'
    help? If you have not looked at this diagram, you may wish to consult it. You can find it on page 165 of the QPIII
    parts manual on Ivan's site (thecarnut.com)...

    Somewhere, I have a diagram of the vacuum system as found on my car (hand drawn by me). I remember comparing
    it to this diagram to some degree. Unfortunately, my car was messed with somewhere along the line, even though it
    was sold and resided in California. I will see if I can dig it up. But attached is a photo of the vacuum line coming out
    of the front of the intake manifold. You can see where it connects to the top of the 3-way switch located at the top of
    the thermostat housing. The middle hose from this switch goes to the emissions/exhaust air diverter valve. This
    seems to be consistent with what is shown on the emissisions/exhaust plate picture from earlier today.

    If I find my diagram, we may be able to tell where the hoses ultimately went..

    Mike
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  14. jamespeter26

    jamespeter26 Karting

    May 9, 2019
    54
    Rome, Italy
    Full Name:
    Peter
    Hi Mike,

    Thanks a lot for your help! I will keep studying these vacuum lines and will see what I can do. If you manage to find your handwritten vacuum diagram, that would be super helpful. Clearly the hoses in my car aren't plugged as they should.

    However I'm now dealing with a bigger problem. A couple of weeks ago I had a carb cleaning & rebuild done by a "professional" carburetor shop here in Rome, and I'm only half satisfied with the work. On the one hand, my carburetors were really dirty and clogged, and the guy told me the jets weren't even the same from one caburetor to another! So he cleaned everything and apparently restored stock jetting (I did verify myself that all idle jets are 60s), plus replacing diaphragms and some other worn parts. BUT - and that's where I am not so happy with their work, and consider that my carbs tuning is ahead rather than behind me: the carbs were totally out of synch, when I took my car back home. I measured over 5 kg/min of air on cylinders 4 & 5, and as low as 2 kg/min on cylinder 2. As you can imagine, driveability was impacted with a lot of hesitation and stumbling.

    I did a basic synch & idle speed setting last week, hoping that this would improve driveability. While there was a clear improvement, it didn't help with the hesitation & stumbling. I just completed 300km this weekend, visiting a friend in Umbria, and after doing both highways and small countryside roads, I can confirm the car drives really bad around 2000 rpm and/or uphill; to the point it stalled when I was driving in a steep, small mountain road, and wouldn't start again for 15 minutes. Fortunately I managed to start it again and we completed our trip, but with a lot of hesitation. The car would reach 150 km/h on the highway, but no more.

    Various indicators, including dry carbon-fouled plugs and fuel spilled all over the air filter box, indicate an overly rich mixture. Given that I witness no difference between fuel pumps, and that idle jets are stock 60s, I'm suspecting the fuel pressure regulator and/or the floats height. My nice-but-not-so-nice carburetor shop has already failed me on the synch, he may also have set the float heights wrong. In any case this is a job I will now do myself - I've had enough of "quick and dirty" jobs.

    Please let me know if you think I should look into other spots. I'd rather double-check everything myself before fiddling with the carbs.

    For the moment, the procedure I am planning to follow is:
    - fuel pressure check, between pumps & regulator, and between regulator & carbs
    - clean fuel pump filter
    - compression test on all cylinders
    - double-check carbs jetting & floats height

    and while I'm at it, given that I already have fouled spark plugs and a brand new set of spare NGK BP6ES, I'll replace all spark plugs and fuel lines.

    Anything I should be mindful of?

    If I need to replace the fuel pressure regulator, would you recommend sticking to the original, transparent model or switching to the 85mm with the metal bowl (see https://www.dellorto.co.uk/shop/car-accessories/fuel-pumps-regulators-accessories/pressure-regulators-and-parts/malpassi-filter-king-pressure-regulator-85mm-with-gauge/ )?

    And here are a few more pictures of the car in its natural habitat and my nicely fouled plug:

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  15. thecarnut

    thecarnut F1 Rookie
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    Apr 22, 2006
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    The Car Nut
    I like using the Iridium version of the NGK plugs. They seem to do better in preventing spark plug fouling and therefore smoother idle.

    https://www.ebay.com/itm/4x-NGK-BPR6EIX-6637-Iridium-Spark-Plug-For-AUDI-MARTIN-AUSTIN-BERTONE-HONDA/383288087351?hash=item593dc01337:g:RpwAAOSwhYNd2NKV

    Ivan
     
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  16. Mexico074

    Mexico074 Formula 3

    Aug 14, 2008
    1,132
    Harriman, TN USA
    Full Name:
    Michael Demyanovich
    Hello Peter...

    I was able to find my hand drawn vacuum routing diagram as found on my car. My car was
    modified somewhere along the line, so this drawing pertains really to my car alone. This
    is particularly noticeable on the lower left part of the drawing showing the air filter covering.
    The flaps on the housing are totally inoperable/useless. You will also note that the carbon
    vapor cannisters are also disconnected/totally useless.

    Please take a look and see if this is helpful....

    Mike
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  17. jamespeter26

    jamespeter26 Karting

    May 9, 2019
    54
    Rome, Italy
    Full Name:
    Peter
    Good morning and happy new year to all!

    I managed to get some time to work on the car last week. Mark thanks a lot for your vacuum diagram, it's indeed really helpful and very similar to mine - except I don't have all the emissions stuff. So if anything, my car is simpler but aside from that looks identical.

    Vacuum-wise, here are my observations:
    - At the rear of the intake manifold (near the firewall), there is a vacuum hose that goes to a 3-way tee. From here, one hose goes to the vacuometer/fuel consumption gauge, and the other one goes to the air pump. Given that the air pump is already disabled in my car (no belt), I replaced the whole thing with one single hose that goes straight from the intake manifold to the vacuum gauge.
    - At the front of the intake manifold, I replaced the short hose going from the manifold to the oil vapors large hose, and added clamps. On the oil vapors hose side, this was really needed as the connector tends to get oily and slippery! I also noticed that the vapors hose itself had a large crack on the underside. I taped it and am purchasing a replacement.
    - Much to my dismay, I realized that the other vacuum lines to/from the solenoid (i.e. between vacuum pump & solenoid, and between distributor & solenoid) are of a smaller diameter than the intake manifold lines. Intake manifold lines had 5mm internal diameter, these ones seem to be 3mm or so but I haven't yet measured. Will replace these ones once I buy the correct hose. However these didn't appear to have cracks, unlike the intake manifold lines.

    Then I replaced my fuel pressure regulator with the 85mm version. Factory set at 2.75 psi, I double-checked with a gauge.

    Then I replaced all fuel lines with Gates Barricade, and replaced the main fuel pump with a Bendix, purchased from MIE. Both pumps were original, but the main pump was showing signs of weakness (from time to time it stopped delivering fuel and the car would stall unless I switched to the emergency pump, so thought it was time for replacement). I was disappointed to find out that the brand new Bendix does not work at all! So now I operate only on the emergency pump, and will sort it out later. I am wondering whether this is due to the Bendix requiring higher current, as compared to the original pump. Will try connecting it directly to the battery and see if this makes any difference. For the moment I'm inclined towards ordering a new Facet Red Top, which is easily available in Europe (could anyone kindly confirm the Red Top is the correct replacement for this car?)

    Compression test was more or less even across all cylinders (dry test between 100 and 130, didn't do the wet test). I replaced all spark plugs with BP6ES which I had at hand (thanks Ivan for the advice on iridium plugs, I may try them next time). My BP6ES were gapped at exactly 0.85 mm.

    Then I ordered another 4 Weber DCNF rebuild kits and double-checked everything inside the Webers, since my car started being rich after a questionable job done by my carburetor shop (following which, if you recall, my carburetors were totally out of synch - my assumption was that, if they missed the synch, they could just as well have done other things wrong). I found that all jets were factory spec: idle jets 130, main jets 135, air correctors 155, and F25 emulsion tubes. Floats were all at 48mm exactly, but they had a reduced travel, going down to 54mm only. I lowered the float level to 49mm and increased the travel to 58.5mm (9.5mm total travel), as per Birdman's excellent tutorial and apparent richness of my mixture.

    After all that, I went for a 50km test drive and... the car still misfires, runs way too rich, stumbles under load and acceleration, and lacks power overall. After 50km, I pulled the plugs out only to find them nicely coated in black, dry carbon - similar to my earlier picture. I was expecting that with brand new fuel lines, correct pressure, and factory carb jetting, the car should be kind of OK and at least ready for fine tuning, maybe even run a bit lean due to nowadays fuel being weaker than 40 years ago. Unfortunately, it felt like I was clearly in the coarse adjustment stage.

    After such an extensive servicing of the entire fuel system, I started thinking that my problem might be elsewhere, and various forum threads made me think that these symptoms could also be caused by a weak ignition coil. I pulled out the multimeter and found:
    - Primary circuit resistance: 0.8 Ohm (should be between 1.8 and 2.2)
    - Secondary circuit resistance: 8500 Ohm (should be between 8500 and 13500)
    I double-checked these numbers with another multimeter I had there, just to be sure, and found the exact same readings.

    I now recall that, when I used a colortune a few weeks ago, I noticed that while the combustion gave a nice blue flame, it would take place a bit erratically, i.e. sometimes there was no flame at all and sometimes a blue flame. This should have caught my attention but for some reason I overlooked it. So it looks like I have a (more or less) correct air/fuel ratio, but a faulty ignition.

    Am I right to assume that my ignition coil is failing due to primary circuit resistance being so low? I already ordered a new coil anyway, and it will be in the car within days. I'll post an update soon.

    On a separate note, I also did the instruments cluster this weekend. Quite a tough one to get out! A few observations, if this can be useful to fellow owners:

    - in my car, there was only one nut to unscrew from underneath, at the back, just next to the speaker (I've read that other cars had two nuts or studs, that is definitely not the case here). To make it easier, it is better to temporarily remove the leather panel covering the steering wheel height adjustment. Of course, you also need to remove the four small screws at the front/bottom of the cluster, near the various dash buttons but these are much easier to do.

    - the illumination panel, which sits at the top of the cluster, contains 4 T5 (12V, 1.2W) bulbs. Total bulbs in the instruments cluster are 23 T5 bulbs, and only one T10 bulb. (The parts catalog says 23 T5 and 5 T10 but I don't know where the other 4 T10 are located).

    - the 4 illumination bulbs are connected via a flexible printed circuit. It is a beautiful part, except that in my case the conductive sections were broken at several places and basically forming an open circuit. I could fit small electric wires between bulbs, as a replacement.

    - the correct odometer gear for a European (kilometer) car is indeed the 20/29, available from SpeedometerGears among others (https://www.speedometergears.com/porsche-odometer-gears) - be careful with the white plastic holder, as it is very fragile and has broken while I was trying to insert the gear (I could repair it using a bit of adhesive tape and super-glue together, we'll see how long this holds)

    - when servicing the odometer assembly, you need to disassemble the tachometer needle and dial. Take note of the position of the needle before doing so, because when zhen putting back the needle, you will need to calibrate it - otherwise it will display an incorrect speed! Best way to do that, when re-assembling the tachometer/odometer, is: insert the needle at a "high speed" indication, and then finger lower it to zero (i.e. rotate the needle counter-clockwise, once in place). Then temporarily reconnect the four instruments cluster connectors, and go out for a drive with Waze or another smartphone app which displays current speed, take note of the difference between GPS-indicated speed and what your tachometer reads, and then go back to your workshop and adjust the needle accordingly. In my case, for the tachometer to display the correct speed when driving, the needle has to rest at "5 km/h" when the car is off. If it rests at 0 km/h, it will read 20 km/h when I'm driving at 25, 50 when I'm driving at 55, etc. Also be careful not to insert the needle too deep when re-assembling it, otherwise it will rub against the dial and will remain stuck. Easy way to test that: if you finger rotate the needle to higher speeds (clockwise), and then remove your finger, it should fall back to zero (or in my case 5 km/h) smoothly and not remain stuck anywhere in between. Same goes for all other gauges by the way, such as the RPM.

    - the vacuometer has a fragile mechanism, which relies on a tiny metallic wire that, in my case, was broken. I could repair it using another piece of metallic wire. It is quite simple, but very delicate and you need a pair of tiny pliers. You can also adjust the "calibration" by bending this metallic wire to the desired length - the shorter, the more the needle will remain in the green area. Many users have reported being unable to get the needle in the green area, this is simply due to the fact that by design, the maximal extent the needle can travel is only half of the dial length (under normal operating conditions, except when you take your foot off the accelerator pedal in which case it jumps back to zero = totally green for a second or so). I calibrated mine to make it travel mostly around the yellow area, with a bit of green and a bit of red. I suspect that factory calibration is mainly around the yellow-red area, hence why no one could get it in the green area. But really, the word "calibration" is inappropriate here - the dial doesn't even have digits, so this is a very approximative indicator of intake manifold vacuum, and as such I prefer to see things in green rather than red knowing that I won't get anything more precise than that.

    Finally I also take this opportunity to announce that, with the help of Ivan Ruiz, we posted the full QP3 electric wiring diagram on Ivan's website. I have an English version hard-copy and sent a scanned version to Ivan. The document contains two parts: a full-size poster, with numbers to identify appliances and wires, and a booklet with an explanation of all the numbers, wire colors, etc. Both documents are available at the following address: http://thecarnut.com/servicemanuals.html .
     
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  18. Mexico074

    Mexico074 Formula 3

    Aug 14, 2008
    1,132
    Harriman, TN USA
    Full Name:
    Michael Demyanovich
    Hello Peter...

    Thank you for all the information! I think it will be quite helpful to all us QPIII owners...

    You refer to a diagram by Mark? Is this a different diagram than the one I posted 12/19?
    If so, could you post a copy here for all of us to see...

    Thanks...

    Mike
     
  19. jamespeter26

    jamespeter26 Karting

    May 9, 2019
    54
    Rome, Italy
    Full Name:
    Peter
    Sorry Mike, I meant you of course! Got confused with Mark's name which appears right under your post.
    Thank you sincerely because your diagram helped me not miss a single vacuum line on my car, I think I've got them all.
     
  20. BobS.

    BobS. Rookie
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    Jun 21, 2019
    40
    Burbank, California
    Full Name:
    Bob Schmitt
    Great technical advice on this forum! This is not technical, but may be of interest:
    The online magazine Vintage Race Cars recently had an article and a video on the Quattroporte:
    "Presidential Limousine Italian Style" and an Italian Video.
    I've cut the asking price on our 1980 Quattroporte - funds will go to the restoration of our 1969 Alfa Romeo Spyder 1750, owned since 1984.
    The is the primary webpage with details on the car: http://1980maserati.com/
    Back to eBay or ??!!
    Thanks!
    Bob S.
    Burbank
     
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  21. jamespeter26

    jamespeter26 Karting

    May 9, 2019
    54
    Rome, Italy
    Full Name:
    Peter
    #1718 jamespeter26, Feb 2, 2020
    Last edited: Feb 2, 2020
    Hi all,

    I'm still working on fixing a few things on the car, but I thought I should post here some additional details on how to repair your broken vacuometer. It is broken on most Quattroportes I have seen, and this is actually one of the most useful instruments I can think of - and a really easy one to repair.

    1. Why do you need it?
    The usefulness of that gauge has been discussed earlier in this thread (see https://www.ferrarichat.com/forum/posts/141989371/). As a fuel consumption gauge, I understand that it is moderately useful - after all, we know these engines love to drink fuel - but it is also, and more importantly, an engine diagnosis tool. Once you learn how to read the various ways a vacuometer fluctuates, this tool can tell A LOT about an engine's condition. The below vacuum gauge chart can help you identify various patterns and their associated conditions. While a professional vacuum gauge has a graduated scale to measure vacuum in inches of mercury, this one is enough to detect if something is not normal and whether you should investigate what is going on.

    2. How does it work?
    The vacuum gauge on our Quattroportes is the only non-electronic gauge of the instruments cluster. It is directly connected to the intake manifold by means of a vacuum hose which goes through the firewall and is hooked to a three-way connector (or T connector), which is then connected to a nipple at the rear of the manifold. There are two such nipples, the other one is at the front of the manifold. The third hose which is connected to that tee goes to the air pump (near the front-left headlight, above the A/C compressor) but since many of us have disabled this air pump, I suggest removing this hose and the tee altogether, and connecting the vacuometer directly to the intake manifold.
    The operating principle is extremely simple: intake vacuum decreases as the throttle opens. Vacuum is therefore high when at idle, and low at wide open thottle.

    3. Why is your vacuometer broken and how do you repair it?
    The vacuometer is actually made of a diaphragm, which rocks a small metallic arm back and forth, and this arm is connected via a tiny metallic wire to the needle. There is also a spring, to oppose some resistance on the needle. The diaphragm pulls the needle towards the green area (more vacuum) while the spring pulls it towards the red area (ambient pressure). Now, usually the spring is still in place, but the metallic wire is as thin as a hair, and a tiny bit of corrosion is enough to break it. This typically makes the needle always point at the maximum "red" and not move at all.

    The good news is that it is easy to replace this metallic wire, and reconnect the central diaphragm arm with the needle. All you need to do is bend a small bit of metallic wire to the correct length, and attach it there. This is a VERY delicate operation and you need to get the length exactly right, which is best done via trial and error, so you want to take your time and be precise.

    Of course, you need to get the instruments cluster out first. That's not an easy thing to do, but I won't cover it here. There is one nut to remove at the back, and then four small screws. There are four wide electric connectors and one vacuum hose to disconnect. Once you have the instruments cluster out, removing the vacuometer is easy but be careful not to bend it.

    You then need to replace this hair-thin metallic link with a new one, hopefully stronger. You will need 13 to 15 millimeters of metallic wire, the type you can easily bend. I found a suitable one in these small, plastic-covered iron wires that come with computer cables when they are new, to hold them together (picture 1), but a paperclip would probably do the trick (might be a bit thick). You will also need the tiniest pair of tweezers you can find to bend it, and then install it in the vacuometer itself.

    First, bend this piece of wire at each extremity, to form two hooks. Then, bend the central section twice to form a loose Z shape (picture 2). If you are successful, you will be able to attach this small contraption where the original metallic wire used to be, in your vacuometer, one hook on the needle side, and the other one on the diaphragm arm (pictures 3 and 4). I found it easier to install it by backing the needle manually towards the green area, and holding it with your finger. This will give you about one millimeter of clearance, which should be enough to put the wire-link in place.

    From there, you can start the "calibration" process. The calibration consists in bending the Z segment in order to shorten or lengthen your wire, i.e. bring the two hooks closer or farther from one another. This will directly affect the "maximum" reading of your vacuometer. Too short, and the resting position of the needle will be in the yellow area, which means the needle will never reach the red area. Too long, and the diaphragm will hardly move the needle away from the red area. Most owners who still have a functioning vacuometer often complain that it is constantly in the yellow-red area, I suspect this is because the original wire has stretched over time.

    Also, I noticed that intake vacuum variations will not be enough to span across the full extent of this instrument. Instead, it will only travel, at best, 1/2 to 3/4 of the full green-yellow-red scale, so you want to set your "maximum" so as to allow the needle to go at least a little bit into the green area, cover the entire yellow area, and go a little bit in the red area. After trying various calibrations, I found it optimal if the "maximum" reading is somewhere in the first half or at the middle of the red area (picture 5), but not resting against the pin which marks the end of the red area. If the resting position is against this pin, the needle will almost never reach the green area when the car is idling.

    The important thing here is : do not try to bend the Z segment while the wire link is installed on the vacuometer. Instead, if the maximum is not correct (which is almost always the case on your first attempt), remove the wire carefully, bend it in the desired direction (shorter or longer), and put it back again. I'm saying that because I realized at my expense that other parts of this instrument are also very fragile. During my first attempt at repairing it, I used to bend the wire while it was installed it in the vacuometer, but I ended up pulling on the needle arm and bending it instead, and it eventually broke. Of course, there is no way of gluing it back or anything, I had to purchase another vacuometer and repeat the same operation, only more carefully. So even if it takes longer, just be patient, and take the wire out to carry out your adjustments.

    To check if you are successful, just put yourself in front of a mirror and suck into the tube. The needle should travel towards the green area.

    4. How do you make the most of it?
    That's the interesting part. While this is a non-professional vacuometer, it has a better purpose than just colorfully decorating your instruments cluster. My advice is: plug a professional vacuometer on the other nipple of your intake manifold (the one at the front), or temporarily fit a 3-way connector in the hose that goes from the rear nipple, through the firewall, to the instruments cluster, and plug your professional vacuometer there alongside the instruments cluster vacuometer. Then, compare the two vacuometers readings in parallel, and take note of how many inches of mercury (inHg) correspond to various positions of the needle in our three-color vacuometer:
    - needle position at idle (normally: steady, somewhere in the green area) = X inHg (should be somewhere between 17 and 21 inHg, but you want to know the exact reading for your particular engine)
    - needle position at the separation line between the green and yellow area = Y inHg
    - needle position at the separation line between the yellow and the red area = Z inHg
    - you may also want to measure inHg corresponding to additional positions, such as needle at maximum/resting position in the red area, halfway through the yellow area, etc. but in the end, you just want to get familiar with this gauge and learn to read what it is telling you.

    Now you have an arguably non-professional, yet permanently available and conveniently located diagnosis tool, allowing you to keep an eye not only on your fuel consumption, but also on your engine's condition. I bet that, if you own a classic Maserati, you are more concerned about the latter than the former. So here how to make the most of this eighth gauge!

    Vacuum Gauge Chart - credits to https://www.classiccarrestorationclub.com/article/engine-vacuum-troubleshooting/#
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    Picture 1 - The ideal wire to use (second best: paperclip or staple)
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    Picture 2 - How to bend this wire (use a pair of tweezers)
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    Picture 3 - The metallic wire installed in the vacuometer (you can see the spring in the background)
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    Picture 4
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    Picture 5 - Optimal resting position
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  22. rs2001

    rs2001 Rookie

    Oct 15, 2018
    2
    Full Name:
    Marcin Mroczek
    Hello All...

    I am rebuilding the maserati quatroporte III engine.

    MASERATI 4PORTE 1982
    VIN ZAMBC1105CA301636
    CAR N. US/3300693
    BODY N./0693

    I would like to ask where can I buy:

    Main bearings central STANDARD SIZE - The engine is late type (Post-1981) production. The main engine bearings set will be the “New Lubrication” type
    diameter of the "nitrided crankshaft" - 76.175mm
    width of the bearings - 15mm

    Thanks
    Marcin
     
  23. jamespeter26

    jamespeter26 Karting

    May 9, 2019
    54
    Rome, Italy
    Full Name:
    Peter
    Hi Marcin,
    Did you try MIE in the US, or Candini or Campana in Italy? They are known to be the largest suppliers of original parts for these cars.
    You can also try Birdcage in France.
    Good luck with the rebuild and tell us more about it!
     
  24. StanT

    StanT Formula Junior

    Oct 10, 2007
    349
    Vienna, VA
    I too recommend MIE, at Maseratinet.com
     
  25. Mexico074

    Mexico074 Formula 3

    Aug 14, 2008
    1,132
    Harriman, TN USA
    Full Name:
    Michael Demyanovich
    jamespeter26: Please keep up the good work and continue to post here! I enjoy
    reading your trials/tribulations/ and successes in this thread! I promise to try
    and contribute where I can!

    Now, I have what I believe is a very simple question for fellow QPIII owners.

    Attached to the trunk decklid are the license plate illumination lights. On my car there
    are two rectangular holes on the outside of the license plate lights. In one of these holes
    I found 2 green wires, none so far on the other side. I consulted the QPIII wire diagram
    and cannot find what these wires would go to. In fact, I find no reference to green wires
    in this area whatsoever. At first I thought there might be two courtesy
    lights there for when the trunk is opened. But again, I see nothing on the wiring diagram
    indicating such.

    What, if anything, do other QPIII owners see or have in these rectangular holes. If need be,
    I can take a picture and post it later or tomorrow..

    Thanks in advance!

    Mike
     
  26. StanT

    StanT Formula Junior

    Oct 10, 2007
    349
    Vienna, VA
  27. barnfieldman

    barnfieldman Rookie

    Apr 18, 2006
    36
  28. F456M

    F456M F1 Rookie
    Silver Subscribed

    Jan 8, 2010
    3,008
    Oslo
    Full Name:
    Erik
    Thanks for sharing. I have seen this specific Royale at the Panini museum in Italy. I believe the separate rear seats is very very rare. It really shots the car! That car has also a more soft edged body than a normal Quattroporte III. In Norway where I am from, there is a 1987 Royale, and that car does not have the soft edged body and standard rear seats. And flat veneer wood trim. While this one have the thick rounded wood just like the Biturbo 430 and 2.24v.
     

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