Early 20's Citroen 5HP. ? ( https://www.citroen-5hp.org/utilities/formhelp.php?category=register&lang=EN&help=vergaser ). All threads are good , float is sound , very little discernible wear on the spindle , no light past butterfly . Float is marked 33GR , TOP and E , Float valve 2.0 , 26-16 on venturi and 70 (I think) on mixture . Bore is 1" and fixing hole c/cs are 1- 7/8" . Be interesting to know if this is specific to Citroen or whether (as someone suggested) they were also used on stationary engines of the period .