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1958 Citroen 2cv Van carb troubles


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I posted this below in the French Automobiles section but would like a quicker response. Forgive me if I should've waited longer on a reply down there before reposting.

 

I have a 1958 Citroen 2cv van that had been sitting for a long time. Not running well, I recently rebuilt the carb but still have issues.

The main problem is upon acceleration, it bogs down and will only run well when I reopen the choke. Once it is completely warmed up (we're talking 15 minutes of driving) it is somewhat better, but I still have to leave the choke open for it to pull on any load - maintaining speed isn't a problem.

Also, placing my hand over the venturi, doesn't stall it and has little effect on its running. Can find no vacuum leaks around base of carb or the manifold itself. 

The carb is a Solex model 28 I believe.

Can you help this novice out? Let me know if more information is needed.

Also, I haven't found any pictures of other 2cvs with the dash layout mine has. I've been told it might be a Belgium made truck but that is not confirmed.

Thank you for your help.

 

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Not following you well. Are you saying it runs better with choke open or choke closed?

 

I would think the choke mechanism needs to be open to run properly after initial start and warmup period.

 

If all else fails, learn to 🤬 at it in French!

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I think you mean half way closed. (pulling the knob  should close the butterfly).

Which probably means it is running lean.

Not being able to choke it out by hand doesn't sound good. Must be letting in extra air somewhere.

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The choke cable does not activate the butterfly. This carb has a something of a fuel enrichment mechanism on its side. The butterfly opens and closes with the the throttle cable. Also, the pictures of the carb are from before I rebuilt it. It is now spic and span with the appropriate kit installed. Sorry for the confusion...

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Looking at the Solex diagram, this appears to be a constant velocity carburetor rather than the style most in the USA are familiar with that contain both  a choking butterfly as well as a throttle butterfly. This carburetor appears to have only the throttle butterfly.

 

The "choke" appears to be a fuel enrichment device, what I would refer to as a starter circuit. This "replaces" the choke butterfly (at least in Europe).

 

Unfortunately, the only service instructions that I have are written in what I believe to be German. Does not "vergasser" equal carburetor? And that is the only German I know, so cannot help on this one.

 

I will comment that virtually all of the Solex carbs, other than the high performance versions, were constructed of some form of metal that wore profusely, and warped profusely. The last one I did was worn so badly in the throttle area, we had to machine a new throttle shaft, and bush the throttle body. The flange was warped so badly that it would not sit on a piece of glass; it would roll off! Once we straightened the warpage, the throttle bore was elongated, and we had to bore the throttle bore oversize, sleeve, and remachine to specification. Because of the above, the carburetor was horribly lean. Once we did all the machine work, the engine ran pretty well.

 

Since I cannot read the adjustment specifications, I could only suggest trying to raise the fuel level in the carburetor by changing the gasket thickness of the gasket below the fuel valve seat; and wish you good luck!

 

Jon.

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Thank you carbking for the explanation and the suggestion. The casting on this one seems quite true and since it does run fairly well with the "choke" partially open, I just might leave well enough alone except for trying the gasket thickness you suggested. At any rate, as long as it goes down the road, it keeps bringing smiles and odd looks! Cheers!

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I agree on warped flanges and throttle bores on pre-war pot metal SOLEX carburetors. But there should not be an issue with your carburetor. This carburetor provides an extra starter mixture when the "choke" is pulled (separate air/fuel calibration in addition).

 

I can help you with technical info and parts for your carburetor and could also do French and German translations if needed.

 

Is it the 425 ccm or 435 ccm engine?

 

PS: Haven't seen a "Duck" on the street for quite a while.....fun.....

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Thanks for the response, Peter R. Here are a couple of pictures for you. Any pointers would be welcome. I believe it is the 425 ccm engine, but I'm far from knowledgeable about them. It is great fun to drive!

 

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Posted (edited)

You're most likely getting un-metered air in the system as mentioned above. I have a vehicle ('61 Mercedes Unimog) with this exact issue going on... The carb I have is a European type Zenith 32NDIX with the enrichment circuit like your Solex instead of a regular butterfly choke.

 

Like you, choking my carb some makes the engine run great, it runs so-so with a miss and hesitation if the "choke" is open. Closing the "choke" totally on my carb kills the engine when warm. After verifying the ignition system and having the carb apart 4 times to verify proper function (float level, no blocked passages, tight throttle shaft, no warped mating surfaces, correct jets, accelerator pump function) I was only left with an air leak in the manifold...

 

I built a 1psi smoke pot to test for any manifold leaks and sure enough I had an intake manifold leak, I would have never found it without the smoke. 

 

I'll be removing the manifold and having it machined flat along with a new gasket.  

 

No amount of carb adjustment solved my issue, I wouldn't expect it to with an intake leak. 

 

I also checked my sparks plugs and I could visually see the effects of lean running on the plugs themselves.  

 

Air leaks have got to be one of the most frustrating issues to track down!

Edited by Lahti35 (see edit history)
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Correct, AZM is a 425 ccm engine. It was used on 1963-70 2CV's. As far as I can tell the AZM engine was originally equipped with a SOLEX 28 BCI carburetor. The one you have is a SOLEX 28 IBC, which is a later model (replacement). There's also a SOLEX model 28 CBI and other SOLEX carburetors that could be used on the AZM engine as a replacement. Let me look up what the difference is between the carburetors and what the internal configuration is supposed to be.

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Thank you all for the information. I had suspected that the engine in mine was not the original (as mine is a 1958 model). Solex BCI, IBC, CBI???? Why not a BIC or CIB, or ICB? Hmm? Ha!

 

As to an air leak, the butterfly shaft (name?) is sloppy in its holes and the seals in the rebuild kit aren't very effective. I didn't know if that leak would be enough to cause my symptoms. Maybe so...

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In 1963 they raised engine power to 16 hp and went from 26 mm throttle barrel carburetors to 28 mm carburetors. Your engine is a 16 hp engine with SOLEX 28 IBC carburetor. IBC, BCI and CBI carburetors are very similar and use the same gaskets.

The difference is that IBC is not furnished with a dashpot, BCI has an external dashpot and CBI an internal one. On some models the venturi tube is firm (e.g. BCI) on others it can be changed, some models have internal idle jets on other models the jet is accessible from the outside etc.

 

Which carburetor model had been used depends on model and year of the engine and on the type of transmission in use (centrifugal or mechanical clutch). A wide variety of different carburetors had been in use on the 2CV and it’s hard to verify a carburetor when the ID tag is missing…..different linkages and levers, LH drive, RH drive etc.

 

If you want to make sure your carburetor is correct for your engine you would have to take it appart and compare its innards with the SOLEX specifications of your particular application.

 

Below you will find some of the 2CV SOLEX specifications.

 

Translations:

a (Ajutage d’automaticité) = High Speed Bleeder

g (Gicleur de ralenti) = Idle Jet

Ga (Gicleur d’air de starter) = Starter Air Orifice («Choke Circuit»)

Gg (Gicleur d’alimentation) = Main Metering Jet

Gp (Gicleur de pompe) = Pump Discharge Jet (controls injection speed)

Gs (Gicleur d’essence de starter) = Starter Fuel Jet («Choke Circuit»)

Gu (Gicleur d’utilisation) = Compensation Jet (corrects idle mixture)

i (Injecteur de pompe) = Pump Discharge Nozzle

K (Buse) = Venturi Tube

s (Tube d’emulsion) = Main Discharge Jet (Nozzle)

P (Pointeau) = Needle Valve Assembly

F (Flotteur) = Float (weight in grams)

Anné de fabrication = year of manufacture

à partir de = from (e.g. à partir de IX-1963 = from September 1963 and on)

sans = without or none

Alésage et course = Bore & Stroke (in mm)

Cylindres = Cylinders

Puissance = Power (HP)

Direction à gauche = LH Drive

Direction à droite = RH Drive

 

Jets are stamped (in hundreths of a mm) e.g. Gg 120 = Main Metering Jet 1,2 mm

Needle Valve Assemblies are stamped in mm e.g. 1,2 = 1,2 mm bore diameter

Venturi Tube casting numbers in mm e.g. 17 = 17 mm diameter tube   

A.jpg

B.jpg

C.jpg

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.....underlined carburetors mean that it is a SOLEX replacement carburetor for the original installation (2CV's also used French Zenith carburetors as original equipment from 1963).

 

.....and yes, I would bush the throttle shaft bores and use a new shaft. Such a leak seams deadly to such a small CID engine.

I have new throttle shafts and special bushings if you need any.

Once you've done it your "Duck" should run again like Smith's cat....

 

 

Sorry, wrong video....(chuckle) 🙂

 

 

 

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Love the videos! I would be interested in the new throttle shaft and bushings. Would these require my modifying the current carb, or are they basically "plug and play?" Also, one of the two screws holding the butterfly won't budge. I'll guess that I'd have to drill it out. Would the new shaft use my old butterfly? Would you have new screws?

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Unfortunately no "plug and play", some machining would be required. I might have new throttle valves too but you can use your old one I'd say. Yes, I have lots of new screws, brass or steel, whatever you prefer. I might also have a used carburetor body that I can bush for you if you can't do it or even a new one or a entire new carburetor. Will have to check what I have and send you some pictures.

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Posted (edited)

Yes, taxable horsepower, not bhp (calculated power for taxing purposes, not technically effective power).

Calculated according to the French CV (Chevaux Vapeur) formula from 1957 based on the 375 ccm engine.

Rule of thumb:  5.7294 x Displacement (in liters)

 

....and no, definitely not measly 16 hp. If you open the hood of that Rocket Duck you will more than likely find four to six 40 mm dual down draft Webers instead a single 28 mm SOLEX carburetor 🙂

Edited by Peter R. (see edit history)
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Posted (edited)

By the way, it is said that Pierre-Jules Boulanger, at that time director of Citroën, urged his draftsman André Lefèbvre in 1934 to design a very low-priced car that offers space for two farmers in boots and 200 lbs of potatoes or a small barrel of wine. The car shall be capable of doing at least 35 mph at a gas milage of 78 mpg and one should be able to drive it on the worst stretches of way. New drivers shall easily cope with it and the suspension has to be markedly well so that eggs won’t break when the car is driven across unpaved rough terrain. The car has to be cheap and appearance doesn’t matter at all.

 

Mission accomplished in every respect...!  

(Well, I doubt that they succeeded in respect of gas milage but on the other hand it looks like they exceeded on the appearance task 🙂)

 

Edited by Peter R. (see edit history)
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zipdang - Here are some pictures of parts that I have. I haven't looked into carburetors and housings yet but will do some carburetor digging tonight.

 

 

 

 

 

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First look to see if there are any air leaks around the base of the carburetor (intake manifold) as was initially the case with both our former 425 cc 1964 2-CV and 602 cc (Big Block?) 1968 Ami-6.

I have a complete Ami-6 Manual in English if I can find it somewhere in my files.

Running at half-choke may be making up for a vacuum leak / too much air at an inappropriate location?

 

Bon Chance !

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18 hours ago, Marty Roth said:

First look to see if there are any air leaks around the base of the carburetor (intake manifold) as was initially the case with both our former 425 cc 1964 2-CV and 602 cc (Big Block?) 1968 Ami-6.

I have a complete Ami-6 Manual in English if I can find it somewhere in my files.

Running at half-choke may be making up for a vacuum leak / too much air at an inappropriate location?

 

Bon Chance !

Merci! No leaks at base of carburetor. The only leak I can find is at the throttle shaft which I'm going to solve first with Peter R.'s help.

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  • 1 month later...

Hello all! Just a quick, but sincere, thank you to Peter R. for locating and sending a carb body from Switzerland for this 2cv. Swapped the internal parts, installed it on the car, and off I went. It runs better than it ever has and it appears my problems (at least this batch) are solved. Thank you again Peter!

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On 6/29/2021 at 7:10 AM, sebastienbuick said:

I apologize for not being able to help you, but I'm glad your problem is resolved ! :)
So the car is running well now ? :) 

No apologies necessary! You've always been great help and I value your interest as well as all of your wonderful contributions to these forums! Tres bien!

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