It's probably Honda-Bond. When I disassembled my D16A6, I had to knock the rear main seal ring and the oil pump off of the block with a deadblow hammer. There aren't any hidden screws once the engine is stripped down to the bare block, so just make sure you've got all the bolts, hold a piece of wood against the inside surface of whatever's around the crank (sounds liek you're talking about the rear main seal ring), and hit it with a deadblow hammer or a rubber mallet. That should pop it loose.

Oh, and the flywheel side of an engine is generally referred to as the rear side, not the front. The front side is the timing belt side.