Solex 34 adjustment

[tomnorth]

Getting close to completing my Lomax 223 which I bought as a pile of parts. The carb is a solex 34 pics 10 and whilst I can start the engine it won't idle. I saw a post from 2013 which indicated the mixture screw at the rear of the engine but mine is positioned at the front. It is possible to fit the carb facing the other way but I could not get the throttle linkage to work that way. So - throttle working, choke cable working, engine starting but not idling. Any advice on adjustments? Thanks Tom

[Lomax76]

Tom,
I am surprise that you have a Solex 34 Pics 10 as this one is for 425cc engine, this is unusual for a Lomax I was more expecting a 602cc engine, this might explain the trouble jetting not big enough for example.
For 602 M4 should be Solex PICS 40 2 or 3 rep 44 or 45
For 602 M28/1 should be Solex PICS 34 4 or 5 rep 4 or 5
For 602 M28 should be Solex PICS 26 35

[hutchii]

Hi
Questions to Lomax76.
I know little or nothing about the carbs mentioned in this topic but can understand your thoughts.
If the aforementioned carb is normally found on a 425 engine, would the manifold from a 425 fit a 602 engine?
If yes, presumably it doesn’t want to run at idle, with the choke off, because of lack of fuel. I.E. weak mixture. Apply some choke at idle would richen the mixture and prove the point?
If the manifold is from a 602, (I assume the fixing is the same for all carbs) it could be for a single or a twin choke carb?
If it’s a twin choke manifold, the alignment of chokes Venturi to the manifold is surely pretty poor?

I look forward to your answers with interest.
Ian

[administrator]

Tom,
Assuming that this carb is for a 'modern' 602cc engine, check the following:

1) Clean out the fuel filter below the inlet pipe on the front of the carb (in the lid)
2) Remove the idle jet from the front of the carb below the inlet pipe. Blow/suck air through this. If this is blocked, then the car will run, but won't idle. You can use the choke to make it fast-idle if this is the case.
3) Check for air leaks by squirting WD40 or similar around the inlet manifold and carb gasket - listen for changes in engine pitch.
4) Only after all of that, try adjusting the mixture screw on the front of the carb. Start by gently screwing it in and counting the number of quarter tuns until it 'just' touches bottom. This can then be used to reset it to the starting position again. There's a bit of tolerance in this, in that the engien will idle 'lumpy' if it's not right, but should just about run. The difference betwen being too rich and too weak is only a fraction of a turn.

[Lomax76]

Ian
The manifold from 425cc wont fit a 602cc engine but there is a specific manifold for 602cc to fit a single chock carbi..

listmoteur.JPG (139.54 KiB) Viewed 20103 times

To Admin
The procedure you are describing is for as you wrote a twin choke carburetor, Thus not valid in this case Tom is having a single choke carburetor "Solex solex 34 pics ref 10". I have rechecked there was such carburetor rep 10 on 602 engine M28/1 AK2 from 1968-1975.

PCIS34 1.JPG (104.78 KiB) Viewed 20103 times

PCIS34 2.JPG (94.31 KiB) Viewed 20103 times

W is the idling mixture screw

[Lomax76]

Next...

34PICSN.JPG (73.38 KiB) Viewed 20103 times

In this set up:
W Idling mixture
Va Idling air

[Ken Hanna]

Hi Lomax76,
I guess you found this information in Haynes, so it's another thing to add to the list of their errata...

Citroen's workshop manual states that the Solex 34 PICS 10 carburettor was fitted to M28/1 602cc engines in AY(Dyane), AK (van) and AZ (saloon) vehicles between 7/1976 and 7/1978.
Jetting would have Solex's reference 193 or 194, depending whether or not a centrifugal clutch was fitted.

Solex 34 carburettors were also fitted to the 435cc engines from 1968 onwards.

Note that these carburettors wre operated by a pushrod, rather than a cable, which is why Tom has had a problem with the linkages.
Years ago, I worked on a Lomax with this carburettor fitted and used a bicycle brake cable, passing around the filler breather, to operate the throttle in 'pull forward' mode.

Ken

Tom,
I am surprise that you have a Solex 34 Pics 10 as this one is for 425cc engine, this is unusual for a Lomax I was more expecting a 602cc engine, this might explain the trouble jetting not big enough for example.
For 602 M4 should be Solex PICS 40 2 or 3 rep 44 or 45
For 602 M28/1 should be Solex PICS 34 4 or 5 rep 4 or 5
For 602 M28 should be Solex PICS 26 35

[Lomax76]

Hi Ken,
You are absolutely right actually I had modified my post accordingly

I have rechecked there was such carburetor rep 10 on 602 engine M28/1 AK2 from 1968-1975.

slightly # years..
This time Haynes cannot be blamed as I have no access to it was my poor memory, beauty of getting old things keep changing.
I like the solution you have suggested might help me one day, if I remember
Cheers
Paul

[Ken Hanna]

Back to Tom's problem, is it possible that the base of the carburettor is warped, due to 'enthusiastic' tightening of the hlding down nuts in the past?
Easy enough to check, using a small syringe filled with petrol, also easy to correct using a large file...
.

[tomnorth]

Thank you all, I am learning by the minute.
Very confusing buying a pile of parts with multiple engines, carbs and manifolds. The only usable manifold was the one with the solex 34 pics10 mount which is why I fitted it.
The engine it is fitted to is an A06/635 which I understand is an M28/1.
Is there any reason why these should be incompatable?
Thanks again for your input - I now realise the throttle mechanism was meant to be operated by a rod rather than cable!