Maserati Mexico Carb Issue/Rebuild...

Discussion in 'Maserati' started by Mexico074, Dec 29, 2016.

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  1. Mexico074

    Mexico074 Formula Junior
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    Aug 14, 2008
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    Michael Demyanovich
    #1 Mexico074, Dec 29, 2016
    Last edited by a moderator: Sep 7, 2017
    Hello All..

    I really couldn't find an existing suitable thread to post this in so thought I would create
    a new one...

    After many, many years, I have finally experienced a problem with my Mexico (AM112-074).
    I went to start it about a week ago, and it just wouldn't start. It's a good thing it didn't,
    because when I opened the hood, I noticed carb no 3 (numbered from front to back) was
    overflowing with fuel.. Not a good scenario.. I suspect either a float issue or something is
    clogged up... Anyway, it has been a number of years since the carbs were rebuilt, so its
    about time that gets done...

    I decided to remove the carbs with the intake manifold as one unit.. It was fairly
    straight-forward. I drained the coolant, disconnected the fuel feed line and all other
    hoses/wires attached to the intake manifold. I removed carb number 4 (at the back) to ease removing
    the nuts attaching the heater valve to the manifold... I then loosened all the bolts and
    nuts connected to the intake and attaching the intake manifold to the engine. The whole
    thing came out without any real trouble!

    Attached are some pictures.. I will have to clean / rebuild the carbs (38 DCNL 5's) and
    have the intake manifold cleaned and all threaded studs checked.. If I run into a
    problem with the manifold, I have a spare from my QP1 engine. The manifolds are identical,
    right down to the number markings on them...

    When I removed the intake and carbs, I noticed fuel was still in the combustion chamber
    aligned with the problem carb.. I suspect some fuel may have made its way to the oil sump. I will
    need to perform an oil change when the time comes as well...

    Probably ought to have the radiator checked as well....

    I am hoping some of you will have some tips or suggestions! I may post questions as
    I progress...

    Mike
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  2. 3500GTista

    3500GTista Rookie

    Dec 19, 2013
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    Good luck. Sounds like a stuck float or open needle seat. Share photos of your car!

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  3. Mexico074

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    #3 Mexico074, Dec 29, 2016
    Last edited by a moderator: Sep 7, 2017
  4. Mexico074

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    #4 Mexico074, Dec 30, 2016
    Last edited by a moderator: Sep 7, 2017
    Another potential problem discovered ! While looking over the valley where the
    intake sits, I began looking at other things and noticed that the alternator is resting
    against the engine block.. I am pretty sure this is not correct!! In fact I think there
    should be a bracket between the block and the alternator..

    I have attached a picture of what I am seeing.. It would be great if other Mexico
    owners would supply some pictures of what they are seeing. If there is supposed
    to be a bracket there (as the QP1/Mexico parts manual suggests), a picture of the
    bracket would be helpful as well.

    This must have existed since I bought the car back in 1998 ! Funny, that it never
    caused a problem, and I never seemed to have had an alternator issue !

    Mike
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  5. Mexico074

    Mexico074 Formula Junior
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    #5 Mexico074, Dec 30, 2016
    Last edited by a moderator: Sep 7, 2017
    I thought I would also attach this picture.. I believe this to be the valve
    to allow hot water to flow to the interior heater. Interesting, that the QP1/Mexico
    parts manual shows 2 of these in the car. I have yet to locate the second one
    of these..

    I suspect this is an often overlooked part, the lever on mine will not budge! Good
    thing I never attempted to use the heater!

    Mike
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  6. 3500GTista

    3500GTista Rookie

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    She's beautiful, Mike. Thank you.

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  8. wilde

    wilde Karting
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  9. Mexico074

    Mexico074 Formula Junior
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    Thank you Charles...

    That is what I suspected !! Your picture confirms it... I may have a spare from
    my QP1 engine I might be able to use... Just need to find it... If I implement the
    bracket, I wonder if I will need to use a different size belt.. I might have some more
    questions for the group regarding this!

    HAPPY NEW YEAR !!!

    Mike
     
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  10. The Surveyor

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    Happy new year Mike.

    Just to confirm, the alternator bracket shown on Charles car is just the same as mine. If your belt is tight with the alternator tight against the block, I'd say your belt is too short.

    Good luck on the carbs too, I replaced the float valves on mine with new after I was getting petrol overflowing. New valves cured it nicely so hopefully that'll be the same for you. Noticed yours doesn't have the thermal isolator spacers between the carbs and inlet manifold, were these only needed on cars from hotter climates, or were the spacers removed to stop the air box rubbing on the bonnet like mine!
     
  11. The Surveyor

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    #10 The Surveyor, Jan 2, 2017
    Last edited by a moderator: Sep 7, 2017
  12. The Surveyor

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    #11 The Surveyor, Jan 2, 2017
    Last edited by a moderator: Sep 7, 2017
  13. Mexico074

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    Hello Paul...

    Thank you so much for the pictures... I do have some good news!! I was able to find
    the alternator bracket from my old QP1, along with the nuts and bolts.. In fact it was
    in the same box as the alternator, which I forgot I had rebuilt some time ago.. So, I
    actually have spares !!!

    Regarding the carb spacers, when removing the carbs from the intake manifold, this is
    the series of gaskets and spacers found, working from the intake manifold up to the carb:

    1. intake manifold 2. very thin gasket 3. a metal type gasket with a tab 4. thin gasket
    5. thicker spacer 6. thin gasket 7. carb

    A couple of questions:

    1. Do you remember what size alternator belt you used?
    2. Do you have a picture of the thermal isolator spacers you are referring to?

    Thanks...

    Mike
     
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  15. The Surveyor

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    #13 The Surveyor, Jan 2, 2017
    Last edited by a moderator: Sep 7, 2017
    I'll have a look for a part reference for the alternator drive belt, I'm sure I have it on a receipt somewhere.

    Here is the spacer as it was when I took it off. Note the sawcut in it, each one was cut and allowed air direct into the manifold which couldn't be right. I filled them in with resin before refitting.

    On mine, this was sandwiched between the carb and manifold with a gasket on both sides. I got 8 new gaskets from the same guys who supplied the float valves.
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  16. lbird

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    Hi Paul, we were puzzled about the sawcut on our set of spacers too. I have actually one complete set with the sawcut and one without, both from Mexico engines. Technically i cannot see any reason why you want to have uncontrolled air coming into the carbs or manifold through this cut. I was suspecting some strange modification from somebody, but it seems like this cut is very common, but was it from the factory? And if yes, why?
     
  17. Quattroporte3

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    Hi Mike,

    I rebuilt my carbs (42 DCNF) 3 years ago and learned a lot in the process. One of the things that was recommended was to replace the needle valves with Grose jets (basically a ball bearing on a spring type of valve rather than a needle valve).

    Can't remember offhand where I sourced them, but if you'd like to know I can dig out the info.

    If you have air coming in anywhere other than the carb throat you're going to have a bear of a time syncing and tuning them! I'd definitely consider replacing the spacers with solid/uncut ones.

    Just a few thoughts on a rainy afternoon.
     
  18. red27

    red27 Formula Junior

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    Hi everyone and Happy New year!
    MIE lists the Griose jets here:

    https://www.maseratinet.com//p-22190-grose-jet-needle-valve.aspx

    AFAIK they are only suitable for DCNF carbs on the late V8, but if anyone knows differently, then I may try them on my 40DCNL 5s as they are currently in bits. I'll check my spacers for that saw cut notch, but I don't remember one when I did the disassembly. It seems completely counter intuitive to have one there...

    Pierce manifold and MIE both do a rebuild kit for the DCNL with sealed throttle shaft bearings, which seems like a sensible upgrade too.


    Wishing all the best for 2017

    Mark.
     
  19. Mexico074

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    #17 Mexico074, Jan 3, 2017
    Last edited by a moderator: Sep 7, 2017
    I did some checking today and have attached the following picture of the gaskets
    I have come across while removing the carb from the intake manifold...

    Looking from the left side of the picture to the right.. The first gasket is a very, very
    thin one, and sits right on top of the intake manifold... The next is a metal gasket/
    spacer housing, with what appears to be a tab to aid removal. The third gasket is
    thicker than the first, and goes between metal gasket/spacer housing and the spacer
    itself. The forth gasket is the spacer or thermal isolator as Paul indicates. The final
    one is the same gasket as the fourth one, and goes between the spacer and the carb
    body. None of the Mexico spacer/thermal isolators have slits in them..

    When I checked my QP1 engine parts, I found the same metal gasket/spacer housings,
    and the spacers/thermal isolators have the splits in them.. A bit odd I think! Does anyone
    else have these metal gasket/spacer housings?

    On some good news, I was able to locate the QP1 alternator bracket and hardware, along
    with a refurbished alternator! Compliments of my QP1 engine! This was good news!

    Keep the tips and conversation coming!

    Mike
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  20. Mexico074

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    oops... I made an error in my last post.. It should read "The final one is the same gasket
    as the third one, and goes between the spacer and the carb body."

    Sorry about that!

    Mike
     
  21. The Surveyor

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    The metal one with the tab looks to have a smaller diameter than the others Mike?

    It's not shown on any parts manual (that I can see) and I'm wondering what the tab is actually for, could it be for a return spring to hook onto or something, rather than just to help with its removal.

    Cheers

    Paul
     
  22. Mexico074

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    #20 Mexico074, Jan 10, 2017
    Last edited by a moderator: Sep 7, 2017
    Hi Paul...

    Sorry for the delay, but got a bit busy! Yes, these metal ones are NOT shown in the
    parts manuals! At first I thought they were put on my car by a previous owner for
    some unknown reason. But when I checked my QP1 stuff, there they were again...
    It's too coincidental NOT to be factory.. Perhaps these were added after the parts
    manuals were created.. I could see that given the Mexico engine is part of the QP1
    manual. So perhaps they were added after the QP1 engine was in production, but
    the parts manual was not retrofitted.

    Attached are 3 pictures regarding these things:

    1. Shows the metal part itself. Note how the ends are turned up, allowing the gaskets
    and thermal isolator to lay in..
    2. Shows the metal part and how I found all the gaskets involved with it. I should
    mention this was the exact layout for each carb.
    3. Shows how the gaskets and this metal piece would be assembled. Obviously, the
    threaded studs on the intake manifold would hold everything in place...

    Mike
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  23. Mexico074

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    #21 Mexico074, Feb 2, 2017
    Last edited by a moderator: Sep 7, 2017
    Carb disassembly is continuing.. What I was not happy about was the condition
    of Carb #4, the carb closest to the fire wall.. This carburetor has been messed with
    somewhere along the line... I have attached 3 pictures.. Picture 1 shows the pump
    rod, pump spring, and retainer.. The assembly at the top is what came out of my car, the
    bottom assembly is from a spare carb I have. I was not happy when I saw that. Picture
    2 is very hard to see because it is blurry. If you look in the square hole you will see
    the mangled starter valves.. In fact the spring, bushing, and clip which sort of sit
    inside this were missing altogether. Picture 3 shows auxiliary venturi's for the carb. Take
    a close look and you will see these have been severly messed with. Not good!!

    Now, it may be true that a lot of these parts were not needed as the choke setup was
    never installed, and I never really had a problem starting the car. But all this combined
    could have led to poor performance of the carb.

    I still have 2 carbs to disassemble, I hope they do not look like this carb!!! But, I also
    think the parts are available, and I do have a spare set of 38 DCNL 5 carbs. I hope
    I am all set !!!

    Thanks for listening to my complaining....

    Mike
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  24. Mexico074

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    #22 Mexico074, Apr 21, 2017
    Last edited by a moderator: Sep 7, 2017
    I am hoping someone can help me identify the following alternator that came
    off my Mexico. There are no identification stickers, labels or engravings on it.
    It also does not match the alternator that came off my QP1. The only thing
    that leads me to believe it might be a Bosch unit is the 4 wire attachment point
    on the back of it. They are labeled B+ , D- , D+, and DF ... According to some
    Maserati electrical documentation from 1964 to 1968, the 4 marked attachment
    points are indicative of a Bosch unit. Does anyone have a clue what this might
    be?

    Thanks in advance!

    Mike
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  25. Mexico074

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    Hello All..

    I wanted to check with you all about radiators on Mexico's and QP1's.. A long time ago,
    I bought a spare radiator for my Mexico (074).. I wasn't really sure I would ever need it,
    so I let it sit.. Well, the other day I came across it and decided to see if it was any good !
    I took to my local radiator shop and had it tested. It is a copper core and apparently does
    not leak. The shop owner thought it would be prudent to check under top and bottom
    covers, and I agreed. I have attached a picture of what we found which is a bit surprising.

    One row of core tubes is exposed, as can be seen in the picture (sort of), while all the rest are under
    the cover with the small holes in it. Again, the core has this setup at both the top and bottom! I suspect
    this was done to keep the flow down, so the coolant would remain in the radiator a bit longer..

    Has anyone come across this before? Is it safe to remove this? Should I put more
    holes in it to increase the flow? I have never seen this before and am not sure how to
    handle this.

    Any and all help is appreciated!

    Mike

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