The Stovebolt Site Forums The Shop Area Engine Shop Carter YF 2100 rebuild

That isn't your needle. It is your pump check needle and that's a different item performing a different function. It goes point side down in the float bowl and if you leave it out, your accelerator pump won't work correctly. Early Carter YF models used a weight and a ball and later models used the needle (all brass). In the diagram you attached, I think this is 34 and 35, although I can't really see that diagram well enough to be certain. You may not have received the right information from the seller. Some sellers of carburetor kits seem confused or flummoxed by data so they just don't provide it or they provide erroneous generic data that may or may not apply to your particular model. This part will fall out if you turn the float bowl upside down and the gasket (if you got the proper one) should cover it when installed correctly.