I bought the special sized bit. I forget the exact size but it's like 17/32" or so.
The super duper bit has three steps on it so it drills a hole into the feed passage but leaves a step for the o-ring to stop against as well as bevel the edge so it doesn't cut the o-ring going into the rail. I don't have that bit, I have a straight bit. So I drilled it slowly and in a learning moment, found that I should of stopped short of drilling all the way through and left the step for the o-ring, but I didn't so I installed some clips on the tops of the injectors that keep the injector from pushing too far into the rail, then I took a dremel and small grinding bit and manually bevelled the edges to slide the o-ring in smoothly. Next time I may use a cut down stepper bit to bevel the edges. This is all done on a Craftsman drill press.
