Maybe this has been done before, carb plugs | FerrariChat
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Maybe this has been done before, carb plugs

Discussion in '308/328' started by AZDoug, Sep 28, 2025 at 4:19 PM.

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  1. AZDoug

    AZDoug Formula 3

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    #1 AZDoug, Sep 28, 2025 at 4:19 PM
    I have always been paranoid about inadvertently dropping something down a carb when i have the air cleaner off.

    Those 1/2 size paper towels rolled up and stuffed into the carb inlets works, but its not ideal.

    I think i am going to spin up some white Delrin plugs, 1.750" OD with a .675" center hole, 1/2" thick, those will seat into the carb inlets keeping anything out and be thick enough to easily remove with fingers.

    I would imagine pro F-car mechanics from the old days had a set of something similar in their toolboxes.

    Doug
     
  2. bjunc

    bjunc Formula Junior

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    #2 bjunc, Sep 28, 2025 at 4:41 PM
    I have ITBs on my 512 BBi, so there's (12) 42mm holes sticking straight up just asking for something to fall right into the cylinder. So I use "CPT" Caplugs; which have a pull tab in the middle. You can get them in pretty much any size.

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  3. AZDoug

    AZDoug Formula 3

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    #3 AZDoug, Sep 28, 2025 at 7:41 PM
    The center venturi tube on Webers that stick up above the carb won't let simple plugs, fit. Thus my need for the .680" hole in the middle.

    Doug
     
  4. AZDoug

    AZDoug Formula 3

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    #4 AZDoug, Sep 28, 2025 at 8:08 PM
    Though those cap plugs may work very well for when the airhorns are still on the carbs.

    Those 16 pesky nuts and washers holding the airhorns, and air cleaner base, on, are things nightmares are made of.

    Doug
     
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  5. bjunc

    bjunc Formula Junior

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    #5 bjunc, Sep 29, 2025 at 6:20 AM
    Yeah, I guess I assumed there was room above the aux venturi to put them in the air horn. Sorry, not super familiar with the carb 308.
     
  6. bitsobrits

    bitsobrits Formula Junior
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    #6 bitsobrits, Sep 29, 2025 at 6:59 AM
    Replace the nuts/washers with nylock flange nuts. 16 pieces instead of 32. Less pesky that way.
     
  7. miked

    miked Formula Junior

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    #7 miked, Sep 29, 2025 at 9:06 AM
  8. AZDoug

    AZDoug Formula 3

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    #8 AZDoug, Sep 29, 2025 at 10:05 AM
    Last edited: Sep 29, 2025 at 10:11 AM
    That is very, very good idea.

    I didn't know such a thing existed.

    Does anyone know the dia and thread pitch for these?

    I see some in McMaster-Carr that may work

    Thanks,
    Doug
     
  9. steved033

    steved033 F1 World Champ
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    #9 steved033, Sep 29, 2025 at 12:37 PM
    M5 x .08

    Amazon has stainless. 30 for $9.

    while you're at it, get a nut driver like this: (5/16" or 8mm)

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  10. AZDoug

    AZDoug Formula 3

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    #10 AZDoug, Sep 29, 2025 at 2:10 PM
    Already have the nut driver. ;)

    McMaster PN 92461A200 for pack of 100 nylock flange nuts, zinc plated steel, they have stainless also, but didn't see the point, vs the price difference.

    The nut driver is too tall for the very most forward nuts, with the deck lid still on the car, so i made 1/4" drive socket with shorty extension welded to it for my 1/4" drive ratchet for those four nuts. I can get the air cleaner box off without any helper for the deck lid, using those tools.

    Thanks for verifying the size, I measured 5 MM, but wasn't sure about the pitch.

    Doug
     
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  11. Alden

    Alden F1 Rookie
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    #11 Alden, Sep 29, 2025 at 2:50 PM
    Get them in steel, so you can attach a magnet to the nut driver or whatever tool you're using to keep hold of them until you can remove them. If you get stainless steel, the magnet won't work.
    Alden
     
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  12. Nuvolari

    Nuvolari F1 Veteran
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    #12 Nuvolari, Sep 29, 2025 at 2:57 PM
    In these days of 3D printing, making something to work would be the work of minutes to draw and then the printer could print it in a few hours with no supervision. That said air cleaners are off with such infrequency (maybe once every few years) that having a specific tool that I need to store and keep track of does not make a lot of sense. Sometimes a piece of tape or a bunched paper towel is the best tool ever.
     
  13. bitsobrits

    bitsobrits Formula Junior
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    #13 bitsobrits, Sep 29, 2025 at 3:43 PM
    Yes! Magnetic steel. That way if you drop a nut down a carb throat, you've got a shot at retrieving it with a magnet.
     
  14. AZDoug

    AZDoug Formula 3

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    #14 AZDoug, Sep 29, 2025 at 3:45 PM
    I keep a small box in the back of the 308 with special little tools, etc, that I made specifically for the car. Its small enough it fits down in the well on the drivers side of the luggage compartment behind the engine, and makes it easy to keep track them.

    A one foot long piece of 1.75" dia delrin rod is about $15, and drilling a 9/16" center hole and parting 1/2" pieces off takes about 90 seconds per piece. I do have a lathe.

    I have a little closable box like that in all my specialty cars for car specific items

    Steel is what i ordered, i didn't think about the magnetic aspect at the time, but it is 100% the best choice

    Doug
     
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  15. miked

    miked Formula Junior

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    #15 miked, Sep 29, 2025 at 9:57 PM
    Another good source for metric hardware is Bellmetric, I have recently accumulated a lot of new nuts, washers and studs for my 308 re-seal project. BTW, most of the studs are DIN939, very close if not exactly identical to the factory dimensions. The first link shows the array of nylon locking nuts available, multiple configurations, heights etc. The second link shows what is available for M5-.8 nylon lock nuts and finishes available, after you check size and finish boxes the spec sheet appears. Shipping, although not as fast as McMaster, is still pretty quick.

    https://belmetric.com/nuts/locking-nylon-insert-nuts/
    https://belmetric.com/nylon-locking-nut-class-8-steel-din-985/?sku=NN5CLZ
     

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