Solex mixture screw

[tomnorth]

Hi, finally passed my msva and now have my 223 registered and on the road. Took it for it's mot a round trip of 94 miles in the foothills of the Cheviots. Almost did not make it with the motor backfiring and hardly pulling on the long slow climbs. when I got to the garage I realised it was running too rich and the tank was not well enough vented.
The mixture screw was having no effect and when I took it out realised the tapered end was missing! So I need a new mixture screw for a solex 34 pics 10 - it's a 4mm thread 0.7mm pitch.
Can anyone help?
Thanks
Tom

[Lomax76]

In case you do not source it in the UK
https://www.franzose.de/en/Citroen-2CV/ ... chtsaetze/

[notsmartcar]

If it’s the same as twin choke ones pm your address and I will post you one

[tomnorth]

Thanks for your help but bit looks like I am out of luck. The usual Solex twin choke has an 'external' mixture screw with a 5mm by 0.5mm pitch thread (I have a spare one of those). My Solex 34 pics 10 has an 'internal' mixture screw with a 4mm by 0.7mm pitch thread.
The Solex 34 pics 6 has an external mixture screw which I hope has a 4mm by 0.7mm pitch thread so I am hoping to find one of those and make a slight modification to the carb body. Failing that I will try and tap out to 5mm by 0.5mm, modify the carb body and fit the twin choke mixture screw.

Failing that......anyone got a spare manifold complete with twin choke carb!

[Ken Hanna]

Tom,
I don't have a spare single choke manifold.
However, after digging around in the sheds for a while, I unearthed the box of single choke carburettors, from which this M4 x 0.7 threaded idle mixture screw has been removed.
You need to check if you can extract the broken tip of the original idle mixture screw, which will involve removing the carburettor and prodding the debris outwards...

Also, I have my doubts as to whether the 'running' mixture was too rich, as normally carburettors need to have the petrol jets enlarged to counter the 'leaning' effect of unleaded fuel to bring the mixture back up to stoichiometric.
If your carburettor has a 155 main jet and an AB air corrector jet, the main jet would probably need to be increased to a 160.

Ken
.
https://flic.kr/p/2kcdMPM

[tomnorth]

Hi Ken
This is brilliant news - I was about to give up my search. I have removed the carb and successfully taken out the tip with a gentle tap with a pin punch.
I am interested in your comments on the jets - mine has a 165 and an air compensating jet marked AC - will these need modified?
The plugs were definitely sooty black indicating the engine running rich and it does confuse me given the tip of the mixture screw was effectively blocking the hole - I assumed this would lead to a leaner mixture?
Are you happy to post the screw and if so my address is 39 Tenter Hill, Wooler, NE71 6DG
Many thanks
Tom

[tomnorth]

Message for Ken Hanna
Ken looking at a previous post you mentioned the emulsifier tube and the possibility of it being blocked/restricted. From the sectional drawing this appears to be largely enclosed and I wondered if you had any thoughts on how to ensure it is unrestricted (without access to ultrasonic equipment).
The sectional drawing shows a 'chamber' underneath the AC jet whereas in mine the AC jet appears to bottom out.
Tom

[tomnorth]

Had to resort to a slight modification to solve this problem. Bought a set of 5mm by 0.5mm taps, drilled out and tapped the mixture screw hole then fitted a mixture screw from a commonly used solex carb. Had to trim the carb casting by about 8mm to accommodate the new 'external' mixture screw.
Seems to work ok.
So - if anyone needs a set of 5mm by 0.5mm taps get in touch - I am unlikely to use them again!

[Ken Hanna]

Tom,
my apologies for not getting back to you.
I've had a bit of a nightmare in the run-up to Brex$it, needing to get three batches of chassis (13 in total) on their way to customers in Canada, Hong Kong and Holland before the great unknown arrived.
Anyhow, good to hear that you've got it sorted.
Ken

Had to resort to a slight modification to solve this problem. Bought a set of 5mm by 0.5mm taps, drilled out and tapped the mixture screw hole then fitted a mixture screw from a commonly used solex carb. Had to trim the carb casting by about 8mm to accommodate the new 'external' mixture screw.
Seems to work ok.
So - if anyone needs a set of 5mm by 0.5mm taps get in touch - I am unlikely to use them again!

[tomnorth]

Post by Ken Hanna » Mon Dec 28, 2020 10:50 pm

Tom,
my apologies for not getting back to you.
I've had a bit of a nightmare in the run-up to Brex$it, needing to get three batches of chassis (13 in total) on their way to customers in Canada, Hong Kong and Holland before the great unknown arrived.
Anyhow, good to hear that you've got it sorted.
Ken

No worries Ken I thought something must have come up. The good news is the car is running so much better now. The other mistake I made was not correctly adjusting the accelerator pump linkage which I think was starving it of fuel.
I am curious about the chassis you build - what are they?
Many thanks
Tom