Well i was just looking at the cams (b16) and noticed there doesn't seem to be any perpendicular surface on the cams to limit lateral movement, i see a spot on the head where it look like oil is fed to one thrust surface but where is the opposite facing surface for thrust towards the crank pulley side of the engine. Guru's lets hear it.

 

I'm no guru, but on the end of the cams by the back of the motor, there are thrust surfaces about 10mm from the end. It's a ridge about 10mm high and 5mm wide and fits into a slot in the cam cap on the end.