I just checked both a Rochester C and Carter YF carbs that I have and the inlet threads are definitely 1/8" female NPT. All of the carbs I have just have an inverted flare adapter on them for connecting the fuel line. The Carter needle valve fitting is mounted vertically inside the top of the fuel bowl and has nothing to do with the inlet fitting. It has no threads on one end where the needle goes, just a screwdriver slot. Here's a shot of the YF rebuild instructions from The Carburetor shop that came with my YF rebuild kit.
So PastorMatt, unless your carb inlet fitting has been overtightened so the female tapered threads are too large to seal, that fitting you have (1/8" NPT on both ends) should work to install the filter on the inlet of the carb. If it leaks, put multiple wraps of teflon tape around it (being careful not to get the tape over the ends of the fitting), and carefully tighten it down.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
