I don't think molasses will help with hardened petrol gum, and I don't think it will penetrate a tight thread. The stuff that works is a spray can of carburetor cleaner, and it is almost miraculous if you haven't used it before. However it can't dissolve what it can't reach, and that may be a problem in this case.
Can you post a picture of the carburetor from underneath, as close as possible, so we can have a look at the "main nozzle" (that is, the emulsifier) and try to work out how it is retained in the body casting? I'm used to them being screwed in. I just can't see it being pressed in because you then wouldn't be able to get it out for cleaning.
