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Weber DCNs onto 1776 Questions

Discussion in 'Performance' started by pat84, Aug 18, 2014.

  1. pat84

    pat84 Member

    Southern Highlands
    Hi All,

    I just picked up a pair of Weber 40DCN14s. Not DCNF the real old 3 bolt base DCNs. I've got manifolds for them but no linkage. For the linkage I was going to try a vintagespeed centre pull as they look real nice compared to the old Scat ones.

    Main things I want to ask is if anyone can give me a rough guide on jetting? I've got a 1776 in a 75 baywindow thats a 5 seater so not super heavy. I didn't build the motor but the cam feels like a W110 possibly 120 and the heads have 40/35 valves and light porting. Not too sure on compression but I know it was built to the same spec as the how to hotrod book describes and its a strong motor. Currently the DCNs have 32 vents so I was thinking 50 idles, 125 mains with a 220 airs. I haven't pulled them down yet so I'm not sure what emulsion tubes are in there but I've been told to run F24s. Does this sound like a good starting point?

    Also does anyone else run these if so what linkage are you using and hows it seem to hold up? Are you forever adjusting it as my Kombis a daily and I do enjoy tinkering but I don't want to play with it all the time. Also were do you source your air filters from?

    Also the manifolds haven't been tapped at all so I'm thinking of tapping all 4 ports and running an X pipe between all four throats to balance them out and allow a decent booster vacuum. I know most people only run off one port but is there any reason not to run a balance tube similar to what you see on ICT's and Kadrons or the factory twin Solex's?

    Any help's appreciated.

  2. vassy69SC

    vassy69SC Active Member

    55 idles and 200 airs as a starting point (maybe even 180 airs)
    I thought F11 was a better emulsion for us.
  3. pat84

    pat84 Member

    Southern Highlands
    Do 125 mains sound about right or do you think I should go up to a 130? I'll pull them down on the weekend hopefully and see what's in there.

    Also is there any reason I shouldn't run a balance tube? There's no air corrector on the old dcn so I figured it'll help even out any differences.

  4. Barry

    Barry Well-Known Member

    Abbotsford NSW
    rough rule of thumb

    4.2 vent = mains
    So - if 32's you want 135's
    IMO 32's is good.

    For IDF's idles = 1.25 body size
    I would start at a 50 - but could be a 55

    Airs ...... 180 fits all :)

    E's I am not sure about
    F11 is for IDF's
    I have been told DCN dont have E's

    Joel over at AVD use to run DCN's
    Maybe give him a PM

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