Not familiar with the B16, but looking at the www.gcp.se parts microfiche:



It's easy to see a couple of suspects.

First off, the shear pin (#16) holding the gear to the oil pump drive. That could let the cam still turn the dist drive, while the oil pump sits still. Of course, migth not be as simple as replacing the pin, depending on why it decided to shear...

The whole intake thing on the bottom may have rattled loose and fallen off. Leaving it sucking air well above the level of the oil.

Something may have happened to the transfer tube - very long on the B16, which reaches around to supply pressurized oil to the block over by the oil filter.

Might be worthwhile pulling the distributor to see if anything looks wrong with the drive gear. Then maybe pulling the side panels off the block to peek inside the sump at the pump, not sure what you can see from them, though.

But for sure, if it's not pumping oil, probably shouldn't run it at all any more until you figure out what's going on. Don't want to turn a bad problem into a catastrophic one by burning up the bearings. Although if it's making lots of noise, you may already be in line for a major rebuild at this point.
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'63 PV544 rat rod, '93 Classic #1141 245 (now w/16V turbo)