I just bought a BDL fuel rail and it came with all the holes taped for a regulator and Gauge but they do not go all the way through. Does anyone know what size I should Drill the hole into the rail? Any help would be greatly appreciated.

 

No one has drilled out a fuel rail for the regulator or F.P. gauge?

 

if it is already tapped be very careful.
the drill size for a 1/8 npt is 21/64

 

So just try and drill it to about the same size as its tapped just try not messing up the threads?