Grooving lifter bores

Yeah - sorry. I confused the lobes with sides...lol.
Driver's side lifters need to be oiled on the interior (valley) side. Passenger's side lifters need to be oiled from the exterior (cylinder bore) side.

Like I said - trying to feed the lifter face from the edge of the bore is as effective as pissing next to a campfire to put it out. The lifter is spinning. At idle it's about 30-40rpm. At 3K it's winging around at 90rpm. That centrifugal force is not letting it get anywhere near the mating surfaces of the lifter face and lobe. The real EDM lifters have the oil hole is placed offset on the lifter base, and is only .010-.12". So the oil comes out and either goes right between the two, or gets flung outward from near center accress the lifter face. That's how it helps. That's pissing right on the fire.