Well, that's the trouble: when turn to the left at medium speed, mi 3CV cough, make carburetor explosion and fails (Solex 34 PICS)
I've changed:
Spark plugs, wires, coil, contacts & capacitor, carburetor. I've also tried connecting the coil directly to the battery.

Another symptom is that the tachymeter oscilates a little bit. I don´t know were is the trouble. I guess that´s electric. But I can´t find it.

Any idea?

Fuel level in carburettor?

make sure the floats are correct and that both plastic floats are there( S American ones sometimes break off)

if the fuel is low as you turn the fuel moves to the RHS float bowl and can affect the carburation of the primary jetting of the carb

try it at wider throttle as that will use the jets on the RHS of the carb

look for loose wires that may move during cornering

Sean

EDIT: 34 was the last single choke?....FAIL!, tho may still be worrth checking the float levels

That would suggest that there's a loose connection somewhere in the low-tension (before the coil) ignition.

Morning folks,
don't tachometers/rev counters usually have their 'sensing' connection on the points side of the coil?

That could explain why hot wiring the coil isn't making any improvement...

Edit; I'd be tempted to try disconnecting the tacho wire, in case it's shorting out somewhere between the coil and the instrument when cornering.
If it was, that would kill the spark.

ken.
( I'd agree with Sean that the single choke carbs are _much_ less sensitive to fuel surge on corners than the twin choke models, but still worth checking that the fuel level in the bowl is high enough.)

Yesterday I've installed a brand new carburetor without change in this trouble. I've tried also feedind the coil directly from the battery. No changes. Today, I will make a new connection between the coil and the points, without the tachymeter.

My twin choke [Solex 26/35 carb.] 2CV had a spate of misfiring on right-hand corners & bends .....[the problem was at its worst when taking a large traffic island at speed .....bear in mind,we drive on the left in the UK]
Anyway .....a new fuel pump solved the problem.
I can only assume that my enthusiastic cornering was causing fuel surge in a carburettor that was only just getting a working amount of fuel delivered to it.

best regards
T.

Done!
It was the tachymeter. I've disconnected it and the problem is gone.

BUT (there is always a but in my activity as mechanic) I've realize that my new brand carburetor leaks petrol. I'm so happy!