Another old brass carb

[Guest Bert New to this.]

I saw Oldbrass carb 1884 and I have the same carb ( in better condition ) with the same question. Could be a Tillotson or maybe a Koala ( Australian copy of tillotson). I am wondering if this is 1910's thru 1920's and what it may have been fitted to? The shiny part on the underside of the air horn has B 4 stamped into it. The throttle body is 1 3/16". The float bowl cover has no letters or numbers cast or stamped.

[Guest Bert New to this.]

I forgot to mention that there's a casting on top of carb between throttle shaft and air horn of a circle with the letters R and T