carb adjustment...

hi all, I have a 1979 sIII 2.25 petrol ex army, my question is how do I adjust the carb, I cant seem to find the adjustment screws, its the original carb, and to get her to run smoothly I have to leave the choke out abit, if I push it shut all the way in, once the engine is warm it stalls... thanks for your time gents, regards fenman...

bottom of carb towards rocker box .check electrics to as weak spark can be compensated by richer fuel