I'm beginning to rebuild a teapot for one of my Y-blocks. The specific carb i have is an ECZ-G model. When i purchased the rebuild kit i noticed that the kit works for many different teapot carbs such as EDB, ECZ, ECU, and ECJ models as well as a whole bunch of models with an R-1094 etc type number.

My question is what do these E and R type codes mean and are they interchangeable from engine to engine?

Steve