246 carb. jet info? | FerrariChat
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246 carb. jet info?

Discussion in '206/246' started by Gary48, Dec 9, 2005.

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  1. Gary48

    Gary48 Guest

    Dec 30, 2003
    940
    #1 Gary48, Dec 9, 2005
    I feel my jetting is a bit too rich on my 246. Any one with info or part no's. and who might carry them.
     
  2. dm_n_stuff

    dm_n_stuff Four Time F1 World Champ
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    #2 dm_n_stuff, Dec 9, 2005
    http://www.carburetion.com/

    http://www.redlineweber.com/

    I got all I needed at these two places. ALthough I'm sure there are others. And now that the factory has gone back to work, the parts may be more readily available.

    I re-jetted my carbs last year. I'll dig out the receipts and post which parts we used later today.

    DM
     
  3. FLYZDINO

    FLYZDINO Karting

    Aug 31, 2005
    71
    #3 FLYZDINO, Dec 10, 2005
    Why are/did you re-jetting?

    And hows the Dino running now?

    I think mine is running rich also, as are many I have read about here on fchat. Why would ferrari send them out too rich?

    I switched to NGK irridium plugs with the wider gap and hotter series and this seems to have helped alot. (MSD ignition)

    Z
     
  4. snj5

    snj5 F1 World Champ

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    #4 snj5, Dec 10, 2005
    Last edited by a moderator: Sep 7, 2017
     
  5. dm_n_stuff

    dm_n_stuff Four Time F1 World Champ
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    #5 dm_n_stuff, Dec 10, 2005
    Thanks Russ.

    I was going to dig that stuff out.

    BTW the car is in pieces, but when it last ran I could certainly keep up with several different 308s out there.

    The Stebro exhaust may help with HP a little too, but the lead mechanic at Algar has done a magnificent job with my car squeezing some extra HP out without spending a million dollars, and while making it run smoother than I could have imagined.

    DM
     
  6. Gary48

    Gary48 Guest

    Dec 30, 2003
    940
    #6 Gary48, Dec 10, 2005
    Yes, my Dino does run rich with just a little too much black soot in the exaust. Runs great and strong but suffers poor milage (around 15mpg) and I have a friend who reports 21 mpg on his Dino. I think I have room for improvement. I have added MSD which completes the burn better. The previous owner of my Dino replaced the old carbs with new and I synct in the carbs after overhaul and the idle jets are adjusted as per workshop manual. The engine was running rich before the overhaul and still is.
    When running there is a small dead spot or non response when the accelerator pedal is depressed slightly at around 2500-3000 rpm. This little glitch disapears with a big foot of throttle. The condition was helped a bit when I put a little more ignition advance into it.
    The carb relacement has me thinking that the jet size is suspect. I never have to choke the engine to start even when dead cold so I think my diagnosis is accurate.
     
  7. Gary48

    Gary48 Guest

    Dec 30, 2003
    940
    #7 Gary48, Dec 21, 2005
    I have checked the jet no's. on my 246 and found that they are stock no's. so I dug out the workshop manual and found that one of the items that cause rich mixture is too high of a float level. I checked and bingo! they were way high and adjusted to stock specs. As soon as the weather gets better we'll give it the acid test. Thanks for the info.
     
  8. Gary48

    Gary48 Guest

    Dec 30, 2003
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    #8 Gary48, Dec 23, 2005
    Nice dry day so out went the Dino. What a difference, I could tell by the way the engine needed a little choke when cold that the readjusted float level, was making an impact. We are running much better when warm and before You could actually watch the gas guage go down. Now I drove probably 20 miles before I saw any change in the guage. When I got back from about a 40 mile drive, with about 2/3's highway I had noticed a huge reduction in the soot in the exaust pipes.
    All you carb guy's check those floats as I am amazed at the difference and will check milage when I fill up next.
     
  9. snj5

    snj5 F1 World Champ

    Feb 22, 2003
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    #9 snj5, Dec 23, 2005
    What also may have happened is the PO replaced the old stock Dino carbs with the more commonly available (and less expensive) 40dcnf - 12 carburretors which has a slightly different progression circuit and will require sl leaner jet setings than stock. It would certainly explain the flat spot.
    Not a big deal, just need to tweak it a bit.
     
  10. Gary48

    Gary48 Guest

    Dec 30, 2003
    940
    #10 Gary48, Dec 23, 2005
    snj5, Thats a very interesting tip, something I had not known. I will try to identify the carbs the next time I have the aircleaner off. Is there any identification tips? Thank you.
     
  11. synchro

    synchro F1 Veteran

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    #11 synchro, Dec 23, 2005
    My guess would have been the secondaries.
     
  12. dm_n_stuff

    dm_n_stuff Four Time F1 World Champ
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    #12 dm_n_stuff, Dec 23, 2005
    40 DCNF 19 were stock on the US cars '72 -74.


    Stock settings on
    DCNF 19 DCNF 12 (according to Haynes)

    choke size - 32 32
    Main jet - 125 125
    idle jet - .55 .50
    emulsion tube - F24 F24
    air corrector jet - 220 220
    accelerator pump jet - .50 .45
    needle valve - 1.75 1.75

    And Russ, where would you get them now? The 12 is the only one available new, right? I guess Ebay would be the place to watch for these if you needed to replace them, but that would be a crap shoot too.

    Exploded drawing here.

    http://www.webernorthamerica.com/pdffiles/40DCNF.pdf

    MERRY CHRISTMAS TO ALL!!!

    DM
     
  13. snj5

    snj5 F1 World Champ

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    #13 snj5, Dec 23, 2005
    yes - great info. I would guess the only place to get -19 carbs would be off a parted out car (i.e. Ebay or similar parts re-seller such as Ahlgrim)

    As you may know, the progression holes drilled into the lower barrell at the factory are specific to each dash model of the DCNF. While the jetting is easy enough to change and interchangable, the drilled holes have to be worked around with the adjustable jetting.

    Good luck!
     
  14. Gary48

    Gary48 Guest

    Dec 30, 2003
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    #14 Gary48, Dec 24, 2005
    Very good stuff guy's, Thanks so much!

    Gary
     

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