Carburetor Issue 32ADF

[SteinOnkel]

Hey guys,

so I haven't given up on this carburetor just yet.

Symptom: Idle is rough, impossible to tune
Cause: Fuel dripping from main jet venturi

Things I know are good:

- Idle cutoff solenoid
- All passages clear
- Emissions junk is removed
- All ignition components brand new, timing set
- Secondary throttle gap
- Primary throttle is not exposing extra holes in the throat (confirmed on bench)
- Fuel pump/pressure
- Installed tune up kit a few months ago
- Float level SHOULD be good

Idle speed bounces between 850-950, engine pulls 19-21" of hg. So that's a bit much.

Here's the kicker: if I block off the air jet (stamped 170) it stops dripping.

A helpful image can be found here:

https://imgur.com/a/VchCdDo

Blue arrow represents where it's dripping from. Red arrow represents the port I block off to stop it from happening.

Any ideas?

Thanks
Steiny

[18Fiatsandcounting]

Since fuel is dripping from the main jet venturi (your blue arrow) at idle, it means that vacuum at that location is sufficient to pull fuel up through the emulsion tube and into the main jet venturi. I can think of only two things that could cause this: 1) the fuel level in the float chamber is too high, thereby requiring less vacuum to pull it out past the emulsion tube, or 2) your vacuum at the location of the main venturi is too high.

Your vacuum at idle does sound a bit high (my recollection is 17-19 Hg), but try this: See if you have a tube somewhere on the intake manifold that you can disconnect and cause an intentional vacuum leak. If you alternately plug and unplug this "leak" with your finger, see if the fuel dripping stops when you open up the leak.

Another suggestion just as a test: Temporarily lower the float level to only about 1/2 inch of fuel in the bowl by bending the float tangs, and see if the fuel dripping stops.

As for your observation about the air corrector jet (1.70 mm) behavior, I have absolutely no way to explain that but will mull it over.

-Bryan

[SteinOnkel]

Brian,

I was at the lake today thinking about this. It's a gorgeous day here in Northern California - much too nice to be bent over a smelly, noisy engine

I think you're right about the float level. You know how they have the little holes on the sides? Well let's say those are completely filled with fuel. Because there is an orifice on the air jet side, it can easily pull fuel through and air through this orifice. But blocking it off seals it, so no drips.

I readjusted the float (it was a little off, but not by much). Then I tried to set the idle mixture and speed again. Here are the results:

https://youtu.be/gEIZ-FCUVtw

I don't get it, still dripping. Pulling a vacuum plug as you said made it idle a little higher, but it was still dripping. As soon as you are off idle, this thing runs like an absolute dream. No misses, no stalls, no hesitation. And it pulls like the ~90hp it should have.

Cheers
Steiny

[wetminkey]

Can't be too terribly difficult to Dx/fix,...at least your car is driveable! Carbs,...
Maybe we'll figure out some answers together!

[18Fiatsandcounting]

Steiny, you indeed have a mystifying problem. My best guess at this point is that one of your emission control systems provided some sort of (calibrated) vacuum leak on the intake, so when you removed all the emission items, the intake vacuum is now higher than the carb was set up for, so you're pulling fuel from the main jets under idle. The fact that the engine idles higher with a vacuum leak tells me that you're running too rich with this leak plugged, which of course is why the idle is crappy. And of course you're running rich because you're dripping fuel from the main jet at idle. Kind of a chicken and egg problem.

Some things to try: 1) lower the float level well below where it should be (all you need is a 1/2" or so of fuel in the bowl to run at idle), 2) if you have some spare idle jets, see if you have a smaller one you could try. I don't recall the normal idle jet for the 32ADF, but it's probably a 55 or 60. Try a 50 if you have it.

And by the way, where are you in Northern CA? I'm in Livermore (an hour east of SF), although currently in San Diego for a convention, and busy enjoying the marina (when I'm not inside the convention center).

-Bryan

[SteinOnkel]

I'm in Santa Rosa. Not too far; my parents used to live in Livermore up until a few months ago. I was there fairly often, about once a month.

I'm beginning to suspect this is the case as well. I'm also going to spray a bunch of carb cleaner, see if I can find a vacuum leak somewhere.

So the manual stats 6-7mm/14mm for the float settings. Do smaller numbers = less fuel? If I knock it down to say 5 and 13, will that result in less in the bowl? Also the measurements are including the gasket?

[18Fiatsandcounting]

You should have looked me up when you were in Livermore!

OK, back to carbs. I'm not staring at a carb right now, but here's what I recall:

After the engine has idled for a minute or so, I turn it off and pull off the top cover/float of the carb. There should be about an inch of fuel in the bowl, perhaps a little less than halfway full.

You set the float level with 2 measurements. Both are done with the carb cover/float in the horizontal position (like it would be installed in the car), and both are done with the gasket in place. The first measurement is the distance from the gasket to the closest surface of the float, when the float is gently pushed up so that it closes the needle valve but doesn't depress the little ball bearing at the end of that needle valve. This should be about 6-7mm. The second measurement is to simply let the float drop down and hang freely, and the distance from the gasket to the closest part of the float should then be about 14mm. Both distances are adjusted by bending the two tangs on the lever of the float.

Hope this helps. -Bryan

[18Fiatsandcounting]

PS: Since the float measurements are set with the float hanging down below the cover, the smaller the distances, the higher the fuel would rise in the float bowl. So, to lower the fuel level in the bowl, you need to increase the smaller measurement. For example, you would increase the 6-7mm to around 10mm. Don't try changes of 1mm or so, as you probably won't see a difference in your fuel dripping problem. Go big!

-Bryan

[SteinOnkel]

I'll hit you up next time I'm out there!

In fact, last time I did take the ol' Italian bucket o' bolts. Had to show it to my dad, he was way into these cars when he was in his twenties.

Anyways...

here's two snapshots I took yesterday before I change the float settings:

https://imgur.com/a/uX0xwKg

This is with the float adjusted to about 7/15mm. I then changed it to 6/14. Did not make much of a difference.

I'll try 9/13 next. Go big or go home, got it!

[18Fiatsandcounting]

The pictures yesterday of the fuel level actually look a little bit too low to me. Certainly not too high. One question on the pictures though: Next to the 170 air corrector jet, there is an opening that looks about 3/16" in diameter. On the primary side of the carb (closest to the 170 air jet), this hole appears to be filled with gas. On the other (secondary) side of the carb, this hole appears dry. I have to admit that I can't remember what this hole does (power enrichment at full throttle?), but I do recall seeing it with some Weber carbs, but I don't ever recall seeing gas in it.

Is it possible that you have an internal leak in your carburetor body? A crack in the inner passageways that is allowing fuel to get to where it shouldn't be?

-Bryan

[SteinOnkel]

From the student handbook:

this passage on the secondary throttle side enriches the mixture at full throttle and high rpm.

It does not say what this does on the primary, but it makes sense now why blocking the air jet keeps it from dirpping.

I think we are on to something here. I bet you it's some sort of enrichment circuit that is being activated even though it shouldn't be. Fast idle or some crap like that.

Or it's like you say and the carb has an internal leak, in which case it's ready for the bin.

[SteinOnkel]

Woah, you can get a Weber 34ADF copy for $175? Why didn't anybody tell me

I'm going to mess around with this sucker a little bit more tonight, but I'm thinking it might be china carb time soon.

[18Fiatsandcounting]

I think we're on to something here. Yes, an enrichment circuit at full throttle and high rpm makes sense, as when you are after maximum power, you want to richen the mixture more than you want under part throttle. The Weber does this by having the main jet and the air corrector jet set for correct mixtures under all conditions, but then a separate enrichment circuit that basically dumps additional fuel into the emulsion tube well, for maximum power.

However, as your student guide states, this should only be for the secondary throttle side. Also, if you look at your picture of the bottom of the float bowl, that hole next to the secondary main jet is where the fuel for the secondary enrichment side enters, while that same hole near the primary jet was never drilled out during manufacture, and so the primary enrichment circuit should be dry.

This probably is how extra fuel is getting into the primary circuit and then dribbling out of the main venturi.

-Bryan

[SteinOnkel]

Mmmhkay this thing has yee'd its last haw.

I pulled the top of one more time and sprayed brake cleaner with a straw into the hole where fuel sits and should not. It start to gurgle and slowly drip through the carburetor. So yeah, this housing is most likely cracked.

Then I went inside, offered the China-Carb-Seller $20 below asking price, he accepted and now I am crossing my fingers. With these things it can go one of two ways: either it's like your iphone and works flawlessly for years or the factory in Shengzhen hasn't been calibrated in ages and you get a paperweight. We shall see.

From what I've read, you're supposed to toss the jets it comes with and jet for a 32ADF on an 1800. Well guess who has a full set of jets for just such an occasion...

[manoa matt]

Two things I would confirm. All your jets are fully seated. The main and secondary jets in the bottom of the float bowl, the two air correctors just under the cap. Then check that the float needle valve housing is fully seated and screwed in tight to the cap. I've had similar issues as you describe from a non-seated float needle valve. Some rebuild kits come with an aluminum washer and some come with a red fiber washer to be placed between the float needle valve body and carb cap. IIRC it was the aluminum washer that was a culprit.

When the China carb arrives, expect to completely disassemble and remove casting flash and manufacturing bits from the passageways.