Weber 32ADFA Woes

[SteinOnkel]

Hey guys,

so before I put this carburettor on the shelf and build some crazy quad carb setup, I thought I would ask the experts here for one more good idea.

Symptoms: Carb drips fuel from venturi onto the main throttle plate at idle. Carb is impossible to adjust. Idles very rough. Cold or at operating temperature barely makes a difference.

Things I've done without any real success:

- new electronic ignition (distributor, plugs, wires, coil, ignitor). Sparks beautifully consistent, set to 10* at idle. Timing makes no difference to symptoms
- new fuel filter w/ internal pressure regulator, carb sees exactly 3,5 psi
- new mechanical fuel pump
- new fuel hoses
- carb rebuild kit installed, float set according to manual
- new carb base gasket
- new intake manifold gasket
- valve play is within spec
- compression is bueno
- all emissions malarky deleted and plugged
- disconnected brake booster
- sprayed ten cans of brake cleaner at the thing, I can't find any vacuum leaks.

Idle speed is 900rpm, mixture screw is 1.5 turns out, but it doesn't really care if it's 0.5 or 4 turns, it runs the same. I see no reason why the jetting etc wouldn't be original. Car is a 1978 california model, bought from new owner.

Would love to hear your thoughts, thanks!

Greetings
Steiny

[manoa matt]

Take off the top via the 6 slotted screws. Check that the air corrector jets are fully seated. I've seen where they were not and fuel was spilling as you described. Also check the idle jet at the tip of the idle solenoid. Confirm it is not clogged and the conical area of the tip of the jet is not worn where it seats in the carb body. I once had an idle jet where the tip was worn on one side allowing bulk fuel to bypass the jet.

If you want all the info on that carb including diagrams, and the factory workshop manual send me an email.

matt.scarton@gmail.com

[18Fiatsandcounting]

I agree with Matt above. Normally, under idle there isn't enough vacuum at the venturis to pull the fuel from them, unless there is something wrong with the main fuel circuit in the carburetor. In addition to Matt's advice, check to make sure that the needle valve on the float really does shut off the fuel to the carburetor bowl, that the float level is correct, float not sticking in the bowl, etc. I know you rebuilt the carburetor, but it can't hurt to re-check.

In summary, it sounds to me like the basis of your carburetor issue is that there's too much fuel in the emulsion tube wells, and it's spilling over into the venturi (or very easily drawn through the venturi with just the teeniest bit of vacuum). That would cause the other symptoms you mentioned, like rough idle, no effect of idle mixture screw, etc.

Another thought just occurred to me: If your idle circuit is totally non-operative, you might be able to open up the throttle plates enough to get the engine to "idle" on the main fuel/venturi circuit, but man, that would be one heck of a lousy idle... Is your idle speed (not mixture) screw screwed in fairly far, that is, can you see that it is significantly opening the primary throttle plate?

-Bryan

[Daddio]

I've run a 32 ADFA on my '70 Volvo (2L) for many years, and replaced the needle valve with a Grose Jet meant for an SU carb (screws right in ) and had to adjust the float level down to eliminate the same dripping of raw gas down the throat; once the level was low enough it worked great.

[SteinOnkel]

Thanks everyone so far! Here's what we are going to try tomorrow:

1. Set the float lower.
2. Once the engine is at operating temperature, take out the adjustment screw for the cold-start fast idle. After studying Matt's excellent literature, I believe this could be the culprit.
3. Carefully inspect the idle jet for abnormal wear.
4. Double-check idle speed screw. Maybe take the whole throttle body out of the car, make damn sure the progression holes are not exposed with the screw 1.5 turns in and then not touch it until it can get to a reasonable idle. That's the only way I know to make 100% sure it isn't running on the main circuit at idle.


Couple of other things to try:

Disconnect the ignition coil and have someone else crank the engine for a good 30 seconds. See if it drips.

Pinch the fuel feed line to the carb shut with some pliers. Obviously the car will eventually run out of fuel, but if the float level is too high it should go like this crappy idle -> decent idle -> slower idle until stall. Correct?

Lastly, what is the best way to defeat the anti-pollution device? I have disonnected the solenoid for it, screwed the adjustment screw for it all the way in and disconnected the vacuum hose running to it. I'm not sure this is correct however, as the diaphram can still act on the throttle blade. Perhaps taking the diaphragm out completely would be the better route? Or perhaps taking the adjustment screw out?

Cheers
Steiny

[manoa matt]

Another thing. Some rebuild kits come with an aluminum washer and some a red fiber washer to be placed between the needle valve housing and carb top casting. If not tightened properly, the needle valve housing can vibrate and loosen. The needle will seat in the housing, but the housing will not be sealed to the carb top allowing fuel to bypass.

Another thing. The idle cut off solenoid. Some rebuild kits will come with an o-ring and a spring washer and a backing plate that partially contains the o-ring. With all those combined, the solenoid will be fully seated against the carb body, but the idle jet tip will not be seated inside the carb, which is more critical. IIRC there is a smaller o-ring mid way up the solenoid that seals within the carb body.

At the back of the workshop manual there are some checks and adjustments for the throttle plate and idle screw you may want to double check.

[SteinOnkel]

What's up, guys?

So, it runs decently now.

We did everything single thing in this thread, double and tripple checked everything. Measured the fuel pressure, the mechanical pos is putting 9 psi to the carb. Great. Had an electric carter flying around the workshop, put that in - 3.5psi. Still dripping

Turned the mixture screw to 3 turns out and the dripping stopped immediately. Okay that makes absolutely no sense, every single carb I've worked on it's been 1.5 turns out. Thanks, Weber.

Oh and also, you have to expose the first progression hole on the carb or else it will not idle. Looking at the schematics, it's just getting more idle mixture. So that's fine.

Runs pretty good now. The brake booster is leaking a bit, as soon as I connect that the dripping is back. But that's only $75 so no big whoop.

Very happy. Thanks to everyone here, I'm going to go drink some beer

Cheers
Steiny

[18Fiatsandcounting]

Ahh, Ein BierStein(Onkel), ganz prima!!

Well, I'm going to go out on a (very shaky) limb here and say that, once you opened up the idle mixture screw a bit, the engine could draw enough fuel for idling from the idle jets (as Weber intended) and thus the venturi (main) jets no longer had to dribble fuel and so they stopped. I generally set the carb for whatever works best for the particular engine and don't worry too much about 1.5 turns vs. 3 turns or what have you. Every engine is different.

Glad you got it running again!

-Bryan