DCNF "Spansil" adjustments

Discussion in 'Workshop Forum' started by tigeravg, Jan 13, 2020.

  1. tigeravg

    tigeravg True Classic

    Location:
    Hangtown, Ca.
    Alrighty Folks..,
    I have searched high and low, and although I can find snippets and references to this topic, I have yet to find an actual diagram or stated number on the float settings of a DCNF 40 with "Spansil" type floats. This is not an attempt to start a discussion on what a bonehead I am for choosing DCNF's in the first place (I get that!)... I would greatly appreciate simple info on the float measurements of this type carb, with this specific type float. Thanks in advance for any constructive input.
     
  2. carl

    carl True Classic

    Location:
    Virginia
    Did you call the folks at Pierce Manifolds?
     
  3. tigeravg

    tigeravg True Classic

    Location:
    Hangtown, Ca.
    Yup. Nice folks, not helpful in this case.
     
  4. Jeff Stich

    Jeff Stich True Classic

    Location:
    Norco, CA
    You probably won't, as most of the DCNF manuals were written when brass floats were the norm. The float level should likely be set the same regardless of the float material. Most of the Weber DCNF diagrams I have show a float setting in the range of 50-58.5mm or so, depending on the carb variation #. I might be able to show the exact diagram you need if you could tell us the carb variant number (ie: 40DCNF 13 or similar) & the diameter of your float (assuming it's the disc type & not the box type).

    For basic float setting, there's this (from the Haynes Weber Carb book):

    40DCNFfloatsetting.jpg

    **Pay particular attention to Step 44 as noted, as the 8.5mm travel for the fuel needle valve stroke is what's key.
     
    Ulix likes this.
  5. tigeravg

    tigeravg True Classic

    Location:
    Hangtown, Ca.
    I have that book and you are right, Jeff...Brass float. My problem is the Spansil type float is a completely different dimention. Therefore the 50-58.5mm measurement is moot. It stands to reason that the measuremnet of the top of the float to the carb top "base" is a much closer representation of a useful number (12mm) if at all. You are also correct in that the 8.5 mm measurement is the key. Therefore I took a large, clear glass bowl, submerging the float so that I could watch the "activation" points, goal being a full 8.5m of travel unhindered and without flooding or ovewhelming the needle valve. I guess that's the best I can do. We'll see. She goes back together today. 60066106172__D5DC424B-2850-4C05-AA84-BF5315929C69.jpg
     
  6. GregS

    GregS ProjectX

    Location:
    Australia
    If you can find a measurement for the actual fuel height in the bowl, you can remove one emulsion tube and measure down to the fuel level. That's what I did with my DCOEs, not sure if it works with DCNFs?
     
    Ulix likes this.
  7. Ulix

    Ulix True Classic

    Location:
    Stuttgart, Germany
    Hi Jeff, do you have specs for the 44 DCNF in your collection? A friend is using these and we weren't able to find anything on these.
    Also, do your sources all show 48mm for the 42 DCNF as mentioned above?
     
  8. Jeff Stich

    Jeff Stich True Classic

    Location:
    Norco, CA
    Sorry, I don't see these listed in my books.

    Yes, 3 of my books show a 48mm float level setting for the 42 DCNF 2 & the 42 DCNF 9.
     
  9. tigeravg

    tigeravg True Classic

    Location:
    Hangtown, Ca.
    Thanks for the efforts, guys. I put those carbs back together today, she fired up and idled nice. Tomorrow I will try to tune.
     

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