Q: I have a Motorcraft 2150 carb and noticed that one of the idle mixture screws is longer than the other. Is this correct or should they both be the same? In fact, I order two from you and one seems to go in further than the other. Is this correct? Thanks for your help. A: Both screws should be the same length. Motorcraft didn't use 2 different sized screws in any carburetor. If the screws go in at different depths in order to get the idle to smooth out and there is more than 1/2 turn difference, then there is something wrong on one side of the carburetor.

Update - Solution to this problem was dirt. Cleaned out and all was well.