Grumpy,
What do the scrapers bolt to? The pan rails?
they either bolt to the block,between the oil pan gasket and the pan or you can weld them to the oil pan rail, on the oil pan,most guys braze or J&B EPOXY THEM TO THE OIL PAN RAIL,on the oil pan, no they don,t touch the rotating assembly, you place them and carefully trim them, durring the engine assembly process, so that while you spin the rotaing assembly the teeth miss the outer arc of the rotation by about 1/8" and they are placed on the side of the engine that sees the rotation upwards from the sump, the idea is to restrict oil flow from the sump following the spinning assembly around in the lower block, it helps skim away and restrict oil falling from the upper engine, to remain in the sump area of the oil pan, after the crank assembly sweeps it into the sump.
that way almost all the oil makes only a 100-250 degree trip around with the spinning crank a single time, before being forced back into the oil pan.
its NOT installed and used as a source of potentially gaining hp as much as it is a way too insure a steady flow of oil to the oil pump, but it tends to reduce pumping losses that dragging oil around with the rotating assembly can produce.