hatepotholez

Car wont run triple webers

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    Hi Guys,

    Just installed a rebuilt set of 40DCOE's. I can't seem to get the car running. Is their only 2 adjustments, the throttle linkage adjustment at the base of the car and the idle mixture screw by the rear. I did notice a few plugs have gas on them and there was plenty of gas in each carb. Is their any other adjustment I am missing? Also what is everyone using to block the fuel first fuel line and the coolant lines to the old SU's? Finally who sells the throttle linkage?

    Thanks!

     

     

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    google searched the linkage kit number from Redline, 99006.729

     https://www.google.com/search?q=99006.729+linkage+kit&rlz=1C1BOFA_enUS494US494&source=lnms&sa=X&ved=0ahUKEwiV2Y_mz_zfAhVM1VkKHSRSCnEQ_AUICSgA&biw=1280&bih=606&dpr=1.25

    @240260280 bought these of mine but I can't remember the name on the linkage arms.

    1488311852688.jpg

    Edited by siteunseen
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    There might also be throttle stops per carb.
    This is a good book on setup.
    https://www.amazon.co.uk/gp/aw/d/1845849590/ref=dbs_a_w_dp_1845849590

    I'd start with making sure the throttles are closed at rest and adjust the linkages so all 3 throttles start to move at the same time.
    Idle mixture screws I think should be a couple of full turns out from fully closed (but not sure of this, I don't have Webers).

    Have a look down the bore of each choke in turn as you open the throttle briskly and you should see a squirt of fuel going toward the engine. (3 pumps should be plenty for cold start even without choke, too many pumps will flood it).
    If the carbs are reasonably assembled and no big air leaks at manifold it really should start like that.

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    There is a lot to setting up triple webers.  In a nutshell:

     

    1. Engine is in good order (valves, ignition, timing, plugs, wires, manifold sealing, etc).

    2. Linkage is non-binding and has exactly the same start, stop, and throw distances on all 3 carbs.

    3. The carbs are in good order.

    4. The jets, chokes, fuel levels, series number, etc are the same on all carbs AND you are in the ball park for jet and choke sizes for your engine/application

    5. You have the tools and knowledge to tune triple webers: http://240260280.com/Tech/Carbs/Weber/DCOE Theory Operation and Tuning.html

     

    Get one of these for sure:

    image.pngor image.png

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    3 hours ago, 240260280 said:

    There is a lot to setting up triple webers.  In a nutshell:

     

    1. Engine is in good order (valves, ignition, timing, plugs, wires, manifold sealing, etc).

    2. Linkage is non-binding and has exactly the same start, stop, and throw distances on all 3 carbs.

    3. The carbs are in good order.

    4. The jets, chokes, fuel levels, series number, etc are the same on all carbs AND you are in the ball park for jet and choke sizes for your engine/application

    5. You have the tools and knowledge to tune triple webers: http://240260280.com/Tech/Carbs/Weber/DCOE Theory Operation and Tuning.html

     

    Get one of these for sure:

    image.pngimageproxy.php?img=&key=a75e82998c691b20or image.png

    Your website is such a helpful resource, i’ve must of been on the site a few times. The first 2 carbs are not squirting from the accelerator pump jet. I cleaned out the jets and removed the accelerator pump with no success. I also then blew compressed air into the accelerator pump passage and the accelerator jet passage still no success. I can feel air coming from the accelerator pump passage to the accelerator jet circuit but no gas. 

     

     

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    7 hours ago, jonbill said:

    There might also be throttle stops per carb.
    This is a good book on setup.
    https://www.amazon.co.uk/gp/aw/d/1845849590/ref=dbs_a_w_dp_1845849590

    I'd start with making sure the throttles are closed at rest and adjust the linkages so all 3 throttles start to move at the same time.
    Idle mixture screws I think should be a couple of full turns out from fully closed (but not sure of this, I don't have Webers).

    Have a look down the bore of each choke in turn as you open the throttle briskly and you should see a squirt of fuel going toward the engine. (3 pumps should be plenty for cold start even without choke, too many pumps will flood it).
    If the carbs are reasonably assembled and no big air leaks at manifold it really should start like that.

    I actually have the Pat Braden Weber book, I also have DCOE’s on my Alfa but I haven’t touch those in years. I think i might be missing the balls that go in the accelerator circuit under the weights because there’s no gas in those circuits. 

    Edited by hatepotholez

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    At least you've got one working one to compare too, and a good book.
    On my Dellortos the problem with the accelerator pumps is always the one way valve gets gummed up if the carbs aren't used for a while and sit with fuel in them.

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    Another good reason to run either 110 or a mix of 110 and 93. Carbs have sat for months and fire up on the first turn of the key (or starter button - race car)

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    ok guys some good news. I got the carbs back from a rebuilder, got the car to idle at 950-1000. It needs some fine tuning. From what I am understanding there are 2 main adjustments, mixture and idle speed(throttle stop). Also I can't get the synchrometer to read below 5 and some 7.

    Also what setup are you guys using for the main throttle linkage return spring? I am using the 280z adjustable hook and I bought a metal linkage(don't want to use the original plastic ball rods) from that to the crank, just need one more metal linkage from the gas pedal to the crank. Does someone sell a kit to mount a bracket on the valve cover and a return spring?  I was told to go to home depot and get a spring, unsure which one to get.

    Thanks!

    Edited by hatepotholez

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    There's mixture screws per cylinder, throttle stops per carb, linkage per carb, possibly idle air bypass per cylinder and idle jets - all affect idle and off idle response. You Deffo need to get same air flow values for all cylinders at idle.

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    Initial Tuning of Weber DCOE or other Side Draft Carbs

    What are the model and series numbers on each of the 3 carbs?  e.g. 40DCOE151

    Important: Make sure fuel level is same on all carbs.  Ignore any web sites that say 25mm  down from jet bridge as fuel will spill into carb throat. ~ 29mm down is where to aim according to many sources.

     

    Idle Balance:

    1. Set all the idle enrichment screws to the same number of turns out.

    • If you have 151's (made in Spain) then turn all the 6 idle enrichment screws all the way in then each turn out 1.75 turns (1-3/4). Also close the air bypass screws.
    • If you have others (made in Italy) then turn all the 6 idle enrichment screws all the way in then turn out 0.75(3/4) turns

    2. Warm up the car, disconnect the 3 push rods, and then adjust the idle air flow for each of the 3 carbs.

    • measure the flow to all 6 carbs
    • adjust the idle stop on each carb so that all 6 are equal in air flow.
    • if the flow between two throats is different on the same carb AND you have 151's then us the air-bypass on the lower flowing throat to increase its air flow to match its partner.
    • if the flow between two throats is different on the same carb AND you have non-151's then you may have a bent throttle shaft and drilling a small hole in the lower flowing throttle plate can bring back the balance. (Don't do this until you take carb apart and inspect for other possible problems like throttle plate wear, etc.)

     

    Off-Idle Balance:

    1. Install throttle arms and make sure they do not push on carbs so as to increase idle rpm or air flow.  These arms should have no influence at idle. You can do this by not tightening the three throttle arms at the main throttle linkage bar on the manifold until all push rods are attached to the carb lever arms.

    2. Have a way to solidly turn and hold the linkage to off idle ~ 2000 rpm and measure air flow.

    3. Note the carb flowing the least and use the turnbuckle adjuster on its push rod to extend the push rod so that the air flow increases.

    4. Loosen all push rods at main throttle linkage bar and repeat #1 to #4 until the off-idle is as balanced as you can make it.

     

    The next tuning steps are to get jets and air correctors right. You need an a/f  wideband O2 setup to do this precisely otherwise note engine note, plugs, and driving and adjust to taste.

    We can give suggestions for jetting if you share engine displacement and mods.

    Edited by 240260280
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    Thanks guys.

     

    they are 40dcoe151’s, Italian made. From what I know it’s a stock cam and engine is stock, I did just install headers 6-1 and a full exhaust from motorsport auto. I believe pipe diameter size is 2.5.

    Edited by hatepotholez

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    IMPORTANT! Do not over tighten any jet screws. Lightly seat them and then back them out as desired. You can damage the precision holes at the bottom if you over tighten them!

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    What are the idle jets, main jet, main air corrector, and choke size?

    This works for a higher compression L24:

     

    40DCOE151 (3)

    30mm Choke

    Fuel Height: ~30mm down from top of body

    Idle Jet: 55F9

    Enrichment Screws: 2.25 turns

    Emulsion Tube: F11

    Air: 170

    Main: 120 

     

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    That's the sort of spring. But you don't have to use it like that.

    Here's how mine is setup with 2 of those springs. You can see them on the linkage by the filter on the cam cover.

     

    DSC_0301.thumb.jpg.0f6bbac535eb1318384a8664c3f78547.jpg

     

     

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    Ok some updates. I installed a home depot spring to the throttle linkage. Then I sent the car off to a specialist.  He got the car running(as did I) but it takes a tremendous amount of gas to get it started and then with the slight touch of the gas pedal the carbs spits like crazy. He put full chokes on and the car wouldn't start, then he started covering some of the carbs air horns while starting it and finally got it running. He stated the carbs are not giving enough fuel to get the car started. He will check if the chokes or jetting needs help.

    Would the idle air mixture screws prevent it from cold starting even if the chokes are on?

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