Air Horn/ Trumpet- Weber 40 DCNL5 for a Mexico | FerrariChat

Air Horn/ Trumpet- Weber 40 DCNL5 for a Mexico

Discussion in 'Maserati' started by remi, Oct 7, 2020.

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  1. remi

    remi Karting

    Sep 18, 2008
    104
    Melbourne, Australia
    Hi,

    The mechanical work on my Mexico is almost complete- but we have hit a snag. When purchased, the car bizarrely had no air-horns/ trumpets installed.

    I sourced some from Carbparts.eu, which seemed to be correct for the DCNL5. The carbs have been overhauled, and the engine is running well; but in re-assembling the airbox, it has become apparent that these trumpets are much too tall. Their total height is 65mm, 55mm to the retaining ring.

    Additionally, there is no notch on the inside of the trumpet to allow it to clear the air nozzle. (Photo attached).

    Have found a photo of some used 40 DCNL5's from a Ghibli, and the trumpets are clearly shorter (photo below).

    I would estimate the trumpets I have are 30mm or so too tall.

    Does anyone know of a source for these correct shorter trumpets for the 40 DCNL5? Have reached out to carbparts again and am waiting to hear back. Pierce manifolds don't have anything for the DCNL.

    Alternatively, if anyone has come up with a different solution, please let me know.

    Thanks

    Remi

    1. Trumpet as purchased (65mm total height, 55mm to ring)

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    2. Trumpet installed: no notch to clear air nozzle.
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    3. Example of 40 DCNL5; clearly a shorter trumpet
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  2. Mexico074

    Mexico074 Formula 3

    Aug 14, 2008
    1,225
    Harriman, TN USA
    Full Name:
    Michael Demyanovich
    Hello Remi...

    Attached are two pictures related to my Mexico, AM112-074, a 4.2L car with 38DCNL-5 carbs...

    The first shows the carbs attached to the intake manifold, but without the spillover tray (or whatever it is usually called) in place.
    The second picture shows one of the car air horns.. My airhorns are notched, and overall length I come up with is 73mm.. Measuiring
    from the bottom of the air horn to the bottom of the ring, I come up with 23mm.. I did not measure the height of the notch..
    I wouldn't think there would be a difference in the overall body height between a DCNL40 and the DCNL38 carb, but I am not sure.

    Not sure any of this helps you, but if you need me to take some more measurements let me know...

    Mike
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  3. remi

    remi Karting

    Sep 18, 2008
    104
    Melbourne, Australia
    Thanks- I may have found the shorter air-horns at Carbparts.eu: just going to measure up with my mechanic...
     
  4. red27

    red27 Formula Junior

    Sep 7, 2010
    829
    London UK
    Full Name:
    Mark Oliver
    I would be interested to see what you find Remi. I am having the same problem locating the stacks for my early Ghibli with 40 DCNL 5.
    I have 2 and am contemplating getting them scanned and produced on CNC. If you have no luck, let me know and if I make them then an extra set will be no problem.

    best regards.
    Mark.
     
  5. remi

    remi Karting

    Sep 18, 2008
    104
    Melbourne, Australia
    Thanks- I have found these... Now, these are much shorter than the 73mm Mike has shown; but as mentioned the 65mm ones I had purchased were far too tall to enable the airbox to be closed. These ones look like they will do the trick- but will have to get the little notches milled in, as they don't have them...

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  6. Mexico074

    Mexico074 Formula 3

    Aug 14, 2008
    1,225
    Harriman, TN USA
    Full Name:
    Michael Demyanovich
    I wonder why on a Mexico, there would be a difference in carb horn height between the DCNL38's and
    the DCNL40's.. I am assuming Remi's car is a 4.7L, but still doesn't explain the height difference.. Anyone
    have any ideas?

    I have a spare 4.2L QP1 engine, also with the DCNL38 carbs, and the horn heights are identical to those
    on my Mexico...

    Mike
     
  7. lbird

    lbird Formula Junior

    Aug 24, 2012
    288
    Germany
  8. Froggie

    Froggie Formula Junior

    Sep 27, 2017
    476
    Belgium
    Full Name:
    Serge
    Could it be that shorter trumpets were chosen by Maserati for the lower powered 4200 engine to keep more torque at the lower end (instead of keeping more power) when decreasing the engine capacity from 4700?
     
  9. Mexico074

    Mexico074 Formula 3

    Aug 14, 2008
    1,225
    Harriman, TN USA
    Full Name:
    Michael Demyanovich
    I enjoy this discussion.. Some very good points... I was wondering the following,
    if the 40DCNL-5 carbs were only used on the 4.7L cars, such as the Ghibli, Bora, and
    perhaps others, perhaps the shorter airhorns were necessary as the hood was lower,
    and the shorter airhorns allowed for more clearance of the air filter housing? Just
    a thought...

    Mike
     
  10. remi

    remi Karting

    Sep 18, 2008
    104
    Melbourne, Australia
    This is interesting- but my engine is the 4.7L... and there is no way the airbox can be closed with the 65mm air horns I had first sourced; they were at least 30mm to tall to close the airbox lid. Have ordered the shorter ones...and will report back!
     
  11. Mexico074

    Mexico074 Formula 3

    Aug 14, 2008
    1,225
    Harriman, TN USA
    Full Name:
    Michael Demyanovich
    Yes, sorry about that, I should have said 'primarily used on the later 1960's cars, such as the Ghibli, Bora, etc'...
    By this I mean, the 4.2L was used on the QP1, Mexico, and later some QP3's.. I am unaware of any other 60's
    and early 70's Maserati cars using the 4.2... I don't think the Ghibli, Bora, Indy, Kyalami, ever used a 4.2L,
    except for maybe a few Indy's, and maybe a few others.....

    Given the block is the same for the 4.2L and 4.7L, and I believe the height of the 38 DCNL and 40 DCNL carb
    bodies are the same, is there a difference in the intake manifold? Can you provide some pictures of your intake
    manifold and airbox.. Would be interesting to see....

    Mike
     
  12. thecarnut

    thecarnut F1 Rookie
    Rossa Subscribed

    Apr 22, 2006
    3,008
    Atlanta
    Full Name:
    The Car Nut
    Most Kyalami had the 4.2 liter engine.

    Ivan
     
  13. Froggie

    Froggie Formula Junior

    Sep 27, 2017
    476
    Belgium
    Full Name:
    Serge
    The early Indy's were all equipped with the 4.2.
    There were 440 Indy's with the 4.2, from the 1100 produced in total.
     
  14. Mexico074

    Mexico074 Formula 3

    Aug 14, 2008
    1,225
    Harriman, TN USA
    Full Name:
    Michael Demyanovich
    I did not know the Kyalami used the 4.2L, there are so few of them...
    So, of the production run of Indy's, less than half were 4.2L. Weren't there a few 4.9L as well?

    At any rate, I am still interested in wondering why Remi's Mexico needs the shorter air horns?

    Remi, in your first post on this thread, you indicate there were no air horns installed on your engine.
    Was the engine in the car? I would love to see some pictures of what your seeing. If I am using the
    taller air horns on my Mexico, with the 38DCNL's, I would think taller air horns should
    be usable on your car.. I would understand if the 40 DCNL's came with shorter air horns off the shelf, and it appears
    lbird's Mexico might have shorter air horns than what are on my 38 DCNL's..

    I like these little mysteries, nuances, etc...

    Mike
     
  15. Froggie

    Froggie Formula Junior

    Sep 27, 2017
    476
    Belgium
    Full Name:
    Serge
    I couldn't say for the difference between air horns in the 4.2 and the 4.7, in particular for the Mexico.

    What I have seen is that the arrangement of horns inside the air filter seems to be the same in the 4.2 and the 4.9 for Indy's.
    See here a 4.2 (unfortunately without horns installed) when the air filter ovoid box is out:

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    Now a 4.9 with the usual (short) horns:

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    Same inside the rectangular air filter box of the 4.9: while there seems to be enough space above the top of the horns to possibly accomodate slightly taller horns, short horns are chosen instead:

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    Btw, there were 299 Indy's with the 4.9
     
  16. Mexico074

    Mexico074 Formula 3

    Aug 14, 2008
    1,225
    Harriman, TN USA
    Full Name:
    Michael Demyanovich
    Hi Serge... Love the pictures..

    Correct me if I am wrong here, but the 4.9L cars used 42 DCNF or 44 DCNF carbs... I know on my
    Khamsin and on my Ghibli SS they are DCNF's... The DCNF carbs have shorter air horns from what
    I have seen...

    I think though that the DCNL's, whether 38 or 40, would have the same air horns, unless Weber supplied
    the shorter horns with the 40's..

    I am still hoping that Remi posts some pictures of his engine bay, engine, carbs, etc.. I would love to see that
    as we don't see enough Mexico stuff here!

    Mike
     
  17. remi

    remi Karting

    Sep 18, 2008
    104
    Melbourne, Australia
    Will do next time I'm at my mechanics- the second photo at the start of this thread shows the 65mm horns installed, and how far they protrude about the air filter box base- a bit too zoomed up to see I agree. Suffice to say, that with that amount of protrusion, there was no question that the lid of the air box can't close. I'll shoot some more pictures when I'm there next. Shorter air horns have been ordered, but won't get here until next week.
     
  18. remi

    remi Karting

    Sep 18, 2008
    104
    Melbourne, Australia
    As promised- photos from today, showing the initial 65mm tall trumpets I purchased, and then with the shorter 53mm installed- key difference being that the taller ones were 55mm tall above the retaining ring, and the shorter only 26mm as per the diagram I included above. No way the airbox would come even close to closing with the taller ones!

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    red27 and Froggie like this.
  19. Mexico074

    Mexico074 Formula 3

    Aug 14, 2008
    1,225
    Harriman, TN USA
    Full Name:
    Michael Demyanovich
    Hello Remi...

    Thank you for posting the pictures! I always love seeing pictures relating to Mexico's...

    Attached are 2 pictures I found of my car - 1 showing the engine with air filter cover in place,
    and 1
     
  20. Mexico074

    Mexico074 Formula 3

    Aug 14, 2008
    1,225
    Harriman, TN USA
    Full Name:
    Michael Demyanovich
    Hello Remi...

    Sorry about that, I fat fingered something and my incomplete response posted, so here goes again:

    Thank you for posting the pictures! I always love seeing pictures relating to Mexico's...

    Attached are 2 pictures I found of my car - 1 showing the engine with air filter cover in place,
    and 1 showing the engine with out the air filter cover (note: not the best of pictures)....

    What I find interesting in your pictures, is the filter seal that surrounds the spill plate...
    Could this be causing your air filter cover from sitting to high? When you purchased the car,
    was the air filter cover in place?

    You will note on my spill plate there is no seal.. What was there was a thin piece of foam which
    I have removed and will replace...

    Mike

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  21. remi

    remi Karting

    Sep 18, 2008
    104
    Melbourne, Australia
    Yep- when I purchased the car the air filter cover, spill plate and seal were all in place- with no trumpets. Although my seal piece may be a bit thick, the taller trumpets were 30mm too tall to close the top of the cover; and the seal is not that thick! In fact, you can see in my second picture that the seal doesn't protrude much above the edge of the spill plate when viewed side-on..
     
  22. Mexico074

    Mexico074 Formula 3

    Aug 14, 2008
    1,225
    Harriman, TN USA
    Full Name:
    Michael Demyanovich
    Hi Remi... Still a mystery to me why the longer airhorns work on my car but not on yours..
    But on the other hand, the main thing is to get the car running so you can enjoy her! Let us know
    how the shorter airhorns ultimately work out for you! Also, saw the pictures of your car on the
    other Mexico thread.. She looks good...

    Mike
     

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