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Oct. 10, 2011 5:59 p.m. tedium850 New Reader

I've been having a strange weber carburetor isuue that I can't seem to get right.

Little history: Car is a 1979 Ford Fiesta with the stock Weber 32DFTA (Actual Weber, not the Motocraft 740). I've refreshed the carb with new gaskets/diaphragm, etc. The car has a header and all the emissions stuff pulled off. (I was running the Motorcraft 740, but found out the main shaft bushings were shot and creating a vacuum leak). The setup is very similar to the standard Weber 32/36 DGV series carbs.

Anyway, I'm running very rich at an idle that I can't seem to get past (and can't pass emissions). I've verified the choke is full open and I have even bypassed the power valve (removed the spring). I am running a 45 idle jet (stock was 50 or 60 depending who you ask - either way larger/more fuel than I am right now), 105 main jet (with a 180 air corrector and F22 emulsion tube). The standard DGV procedure says I should go to a smaller idle jet, but I haven't seen any smaller, plus I "should" have to be richening it due to the header.

Any ideas? Thanks for your help.

Dan
Oct. 10, 2011 7:07 p.m. 02Pilot Reader

DFT is an emissions carb, but this shouldn't be a major factor. Set float levels - this is a key first step on Webers. Ensure that the needle and seat are free and clear. The idle mixture screw is probably under a tamper-proof plug near the base; remove the plug and access the screw. Normally these are set to run on the lean side, but this may no longer be valid if you've capped all the vacuum connections on the carb base. Adjust for best idle with the mixture screw, then adjust idle speed. Make sure the ignition timing is properly set as well.
Oct. 10, 2011 11:00 p.m. jimbbski Reader

You said the car has all emissions stuff removed so I assume the cat is gone as well. If it is then how can you pass emission without it? I owned 3 Fiestas, a 78, a 79, & a 80 model. I was able to pass emissions with all the smog stuff removed except the cat, and I use the same carb as you have.

I agree with the suggestions 02Pilot posted. You can try adding a bit of timing over the stock setting if you put in higher octane fuel for the test. It may help by starting the ignition prosess a bit sooner.
Oct. 11, 2011 6:59 a.m. 44Dwarf Dork

Pull the air cleaner off look down the throat now look for two small brass jets off to one side (outside choke area) if theses get clogged or just covered you'll run rich. There air bleeds for the Emulsion (sp?) tubes. BTDT Had one E36 M3ty alum base air cleaner that would vibrate loose and the dust would mix with vapors and form a gray slurry and plug them up once a month..

44
Oct. 11, 2011 7:56 a.m. 93EXCivic SuperDork

jimbbski wrote:

You said the car has all emissions stuff removed so I assume the cat is gone as well. If it is then how can you pass emission without it? I owned 3 Fiestas, a 78, a 79, & a 80 model. I was able to pass emissions with all the smog stuff removed except the cat, and I use the same carb as you have.

I agree with the suggestions 02Pilot posted. You can try adding a bit of timing over the stock setting if you put in higher octane fuel for the test. It may help by starting the ignition prosess a bit sooner.

No emissions testing in TN.
Oct. 11, 2011 7:59 a.m. tedium850 New Reader

Thank you all, that gives me a little more to look at - I'll definately check the small brass jets. To answer some of the questions: I have re-set the float level to the specs (I think it was 7mm from ther gasket face if I remember correctly. I even re-set the float "drop" to the specs. The tamperproof cap is gone and right now, and the idle mixture screw is set out only about 1/4 turn off "snug" (should be around 2 turns out) because it is so rich at an idle that it runs rough - it actually runs a little better with the idle mixture screw completely shut off. That's why I thought the powervalve was malfunctioning. Timing is set to spec, choke open, warmed up, etc I do still have a cat (less than a year old Walker universal 3-way sized upt to 4500GVW) The car passed emissions about 6 months ago on the Motocraft 740 (off a 1983-ish Escort), but it started running badly and I found the bushings on the main throttle shaft to have too much play even though it was marked as a rebuilt carb. I may end up just getting bushing for that carb or getting a DGV for it. Within the last two weeks, the carb has been completely disassembled and soaked overnight in a parts cleaner, then sprayed out with carb cleaner to ensure the passages are clear (I must have missed one though), then all new diaphrams/gaskets installed.

What I find odd is that the stock idle jet was a 50 or 60 (.5mm or .6mm) and I am running a 45 (.45mm) jet and still rich at an idle. It seems like I HAVE to have a passage clogged or I'm missing something. I am a touch on the lean side once I get to the primary and secondary main jets though. I've always been told I have to get the idle circuit correct on a weber before going on to the mains (unless the mains are WAY out which aren't in this case).

Thanks again!

Dan