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Thread: 40DCOE Webers vs. ZT

  1. #1
    z newbie yoogener's Avatar
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    Jan 2004
    Los Angeles

    Default 40DCOE Webers vs. ZT

    I have a set of 40DCOE Triple Weber carburetors on an E42 head. They work fine and haven't had to retune them after buying the car from the previous owner just last year. My brother had just cleaned them out and everything still works fine. I'm debating whether or not I should sell these and invest in a set of ZTherapy's. My car does feel very powerful with the Webers but it eats heaps of gas. Since mine is only a street car (occasional track), I'm willing to sacrifice some power for more mileage. How much power do these Webers give if tuned properly, and how much power do ZT's give?

    If you guys think I should sell my Webers for the ZT's, how much would they sell for?

  2. #2
    Ben Chu Ben Chu's Avatar
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    Apr 2005
    Honolulu, HI


    You can tune Webers for milage as long as you do not try to race with it. When I initially started with main jets of 115 using the F11 emulsion tubes I was getting over 23 miles per gallon. However with that setting I was getting some hesitation. I switched to 130 mains, F7 emulsion tubes, 175 air correction, 30 chokes, F9-45 idle and the car runs great on the road. If you run lean, the milage is great. However since with Webers you can't use the vacuum advance milage can suffer. You will need to increase the static advance so that the total advance is around 36 degrees.

  3. #3
    zguitar71 zguitar71's Avatar
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    Dec 2004
    Missoula, Montana


    If you do not have a big cam (larger than a MSA stage 3) then you can make quite a bit of power with the ZT's. I have them and they work great but milage is not so good. If I stay out of the throttle then i can get close to 20 MPG but all it takes is a couple of times hard on the gas and the milage is shot. I quit worring about milage, I got 14 on the last tank but that was with 2 autox races and my foot was in it for the rest of the tank on the street. I would keep the webbers, aint broke don't fix it applies here. +they are great carbs.
    Did I hit that cone?
    1/71 series II 240z, 920 gold (AKA baby poo yellow, but I love it anyway)
    Christopher Gray

  4. #4
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    Jun 2002
    Brisbane, Australia

    Default Weber verses SU carbs

    I have a 240Z with 2.8 mechanicals and 71 SU type carbs. I keep thinking that I should change the SU's for 3 Webers. However the engine will rev to 6500RPM and does not run out of breath so obviously the carbs are doing the job. My 240Z will potter around in traffic and will keep up with any of the triple weber cars on sprint day. I know there is more that can be done to the engine as I am currently getting 140 HP at the wheels as per dyno report. However you have to have a balance between a road and race car.
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