Weber 34 ADF Tuning

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bartigue
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Re: Weber 34 ADF Tuning

Post by bartigue » Tue Jan 30, 2018 9:09 pm

Thanks for the update. This is certainly something I've never seen or heard of, someone adjusting the secondary stop. It would have been obvious upon inspection, too bad we couldn't figure that for you first. Glad its working out.
-----------------------------------------------------------
Brad Artigue
1982 Spider 2000
I've restored, worked on, sold, bartered, and bled for:
1970, 1979, 1980, 1981, 1982 124 Spiders -- 1969, 1970 850 Spiders -- 77 X1/9
http://fiat.artigue.com
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atruscott
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Re: Weber 34 ADF Tuning

Post by atruscott » Tue Feb 20, 2018 8:18 am

Guessing here.... someone mistook the secondary stop for the idle screw at some point in the carb’s heritage? Given the idle screw on a 34ADF is somewhat tucked away.
1970 238 Camper OHV
1974 124 Wagon TC (shortly to depart...)
1974 124 Special TC
1975 124 Sport Coupe
1976 124 Sport Spider (The Racer)
1981 Spider 2000 (The Resurrected)
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covesurfer
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Re: Weber 34 ADF Tuning

Post by covesurfer » Sun Mar 25, 2018 10:54 pm

I debated opening up a new thread, but I guess I am still getting this carburetor dialed in, so thought I would just post here. I am still having a bit of a flat spot when I first press the throttle, or when I shift to 2nd, etc. Basically the throttle bottoms out, then surges after a brief pause. I think the jetting is correct (see earlier on in the thread) so am wondering what other causes there might be. I did swap out the accelerator pump with one from my old 32/34 ADFA, same size (50) but looked cleaner/clearer. I did rebuild this carb so don't think it is the diaphragm, but can double check. The only other thing I though about is that the idle is pretty low - right around 400 RPM vs. 850 or so. Would upping the idle speed help out?
Daniel
Frisco, TX
1977 124 Spider
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bartigue
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Re: Weber 34 ADF Tuning

Post by bartigue » Mon Mar 26, 2018 6:30 am

Yes on the idle speed, if it isn’t set correctly then the throttle linkage mechanism is not engaging at the right point.

Flat spots like that are often caused by the accelerator Jet or the secondary idle jet being clogged.
-----------------------------------------------------------
Brad Artigue
1982 Spider 2000
I've restored, worked on, sold, bartered, and bled for:
1970, 1979, 1980, 1981, 1982 124 Spiders -- 1969, 1970 850 Spiders -- 77 X1/9
http://fiat.artigue.com
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covesurfer
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Re: Weber 34 ADF Tuning

Post by covesurfer » Mon Mar 26, 2018 6:26 pm

Thanks as always! I'll get the idle adjusted, check the secondary idle jet and see if that changes anything.
Daniel
Frisco, TX
1977 124 Spider
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covesurfer
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Re: Weber 34 ADF Tuning

Post by covesurfer » Mon Apr 02, 2018 6:44 am

I checked / cleaned the jets and made sure the pump circuit was working properly. Things are better but I’m still seeing some hesitation. Any other ideas?
Daniel
Frisco, TX
1977 124 Spider
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bartigue
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Re: Weber 34 ADF Tuning

Post by bartigue » Mon Apr 02, 2018 3:13 pm

See if it helps to put the 140 air corrector back on the primary side. I would also suspect the lowest progression hole may be snotted up, these aren't the easiest to clean out as they are cast into the carb body. You can put the little hose from a carb cleaner can in the top of the air corrector and blast carb cleaner while rotating the throttle. It'll spray up - cover it while you do it with a towel or something like that.
-----------------------------------------------------------
Brad Artigue
1982 Spider 2000
I've restored, worked on, sold, bartered, and bled for:
1970, 1979, 1980, 1981, 1982 124 Spiders -- 1969, 1970 850 Spiders -- 77 X1/9
http://fiat.artigue.com
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covesurfer
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Re: Weber 34 ADF Tuning

Post by covesurfer » Tue Apr 10, 2018 10:06 pm

Done and done. I misplaced the original 140 air corrector so had to order one. Sprayed copious quantities of carb cleaner. So far so good; I'll report back if anything changes. Here are my carb specs, for posterity:

Main venturis 24/26
Aux Venturi 4.5/4.5
Main jets 125/140
Emulsion tubes F11/F75
Air Correctors 140/180
Idle jet 50/90
Pump Jet 40
Float Valve 1.75

Thanks Brad!
Daniel
Frisco, TX
1977 124 Spider
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bartigue
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Re: Weber 34 ADF Tuning

Post by bartigue » Wed Apr 11, 2018 1:16 pm

Awesome!
-----------------------------------------------------------
Brad Artigue
1982 Spider 2000
I've restored, worked on, sold, bartered, and bled for:
1970, 1979, 1980, 1981, 1982 124 Spiders -- 1969, 1970 850 Spiders -- 77 X1/9
http://fiat.artigue.com
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