Solex emulsion tube well 

The emulsion tube screws into this well

As used in these carburettors:

22IAC; 
26IAC; 26ZIACO; 26ZIC; B26ZIC-2; 26ZIC-3
30PAAI – in Rover only;
32BI; 32BIO; B32BIO-2; B32BIO-4; B32RBIO-2; 32BIP; B32BIPO-2; B32BIPO-4;
32PAIAT – primary barrel  in E10481; E14544 only
C32BI; C32/30BI; C32BIC; 32BIO; 32PBI-2; 32PBI-5; C32PBIC; C32PBIC; 32PBICC; 32PBICA; 32PBICT;
B32PBIO-4; B32PBIO-7; B32PBIS; 32PIBT; 32PICB – E10429; E10441 only
32PICBT – SpecOE26;
34PBIC;
B40PAIO-5; B40PAIO-5A   

Overall length 43.25mm

Brass section diameter 7mm

Internal thread 1/4” diameter