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Thread: 280z triple webers, haveing some issues

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    Default 280z triple webers, haveing some issues

    I have weber 40dcoes on a stock l28. the jets in the carbs are,
    idle jet-50f9
    main jet-130
    air corrector jet-170
    emulsion tube-f15
    pumpjet-45
    needle valve-175
    startjet-100f5
    chokes-40's
    fuel pressure is at 3.2ish psi
    I have a carter fuel pump which is about 80gph ( should be enough for these carbs) and a msd coil. and i have a aem Wideband afr gauge, now my problem is, at idle my AFR ( Air fuel ratio) is normal (13-14) and when i give it gas it runs LEAN and sputters and dies. if i adjust the AFR at idle and make it rich ( 10-12) and give it gas it runs decent (12-13) but at idle its pig rich and washing my cylinder walls with fuel. and if i floor it from idle it runs lean and dies. Im thinking i need smaller idle jets? also heres a picture of my fuel setup.
    Last edited by katastrophiik; 04-23-2012 at 03:47 PM.

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    Registered User Travel'n Man's Avatar
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    Default

    Freddy -
    Have you researched any for a Weber manual - there is a formula you use to get the correct jets and chokes for Webers - if you research I'm sure you can get you Webers dialed in.

    There is a lot of info on this site - try the search feature first - if all else fails MSA sells info as well as this:
    http://www2.cip1.com/ProductDetails....e=ACC-C10-9696
    Life's a journey; enjoy the ride!

    Mitchell
    L28 - N42 Block w/Flat tops - N42 Rebello Head & Cam - Triple 40 PHH Mikuni's - Headers - Recaro Seats -
    R180 3.9 Diff - Close Ratio 5 Speed - Toyota Vented Brake Upgrade w/ Porterfield High Performance Pads & Shoes

    1972 Datsun 240z
    HLS30-75040


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    Default

    I have the book but the book only says 240z and 260z. And im a bit confused. Im just trying to get it to run decent..i remember there was a website that have setups for the webers but i can not seem to find it again

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    Registered User Mike W's Avatar
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    This post helped me out a lot and has some very good rules of thumb to begin the tuning process.

    Hope this helps.

    http://www.classiczcars.com/forums/s...t=weber+tuning

    Mike.

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    You know once you get your jetting set and chokes confirmed you have to balance your air flow between all three of three of them.

    Do you own one of these? If not go ahead and buy one - you will need it sooner than later.
    http://vwparts.aircooled.net/Snail-T...K-p/ste-sk.htm
    Life's a journey; enjoy the ride!

    Mitchell
    L28 - N42 Block w/Flat tops - N42 Rebello Head & Cam - Triple 40 PHH Mikuni's - Headers - Recaro Seats -
    R180 3.9 Diff - Close Ratio 5 Speed - Toyota Vented Brake Upgrade w/ Porterfield High Performance Pads & Shoes

    1972 Datsun 240z
    HLS30-75040


  6. #6
    Registered User Travel'n Man's Avatar
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    You know once you get your jetting set and chokes confirmed you have to balance your air flow between all three of three of them.

    Do you own one of these? If not go ahead and buy one - you will need it sooner than later.
    http://vwparts.aircooled.net/Snail-T...K-p/ste-sk.htm
    Life's a journey; enjoy the ride!

    Mitchell
    L28 - N42 Block w/Flat tops - N42 Rebello Head & Cam - Triple 40 PHH Mikuni's - Headers - Recaro Seats -
    R180 3.9 Diff - Close Ratio 5 Speed - Toyota Vented Brake Upgrade w/ Porterfield High Performance Pads & Shoes

    1972 Datsun 240z
    HLS30-75040


  7. #7
    Registered User LeonV's Avatar
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    Default

    A couple of things here...

    Weber manuals can help understand carb operation but that's about it. Calculators can only get you in the ballpark. Join "Sidedraft Central" on Yahoo and read the White Paper. If it's hard to follow, then read up on Weber carbs to understand how they work first. Carb tuning is very logical and an iterative process, but is not a mystery. Sounds like you have a wideband O2 already so that's a good start.

    FYI, that syncrometer is great but can be had for way less than $50. Search around and you can find them for $32-35.

    e.g. http://www.texasaircooled.com/catalo...1-30-kg-h.html
    2/74 260Z

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