If the 46 216 is like the 49, the rocker oil line travels through the block so the fix will be alittle more detailed to replace that line.
The oil line connects to the oil distribution block on the drivers side, travels through the water jacket in the block and exits in the pushrod gallery on the passenger side. It then bends it's way arund a couple pushrods then up through the head and connects to the rocker shaft. It's a long one piece line with several fittings to connect to and seal at the block and connect at both ends. It's a one use part and usually must be replaced if it fails along it's circuit.
I had to replace the one on my 49 and it took around 3 hrs total. It's sold as a kit by most of the on-line parts houses.
What happened to mine was a pushrod rubbed a hole in the line and it eventually broke at that point. I had the same symptoms as you describe.
Once you pull the side plate you'll see the line and how it connects on that side. Unfortunately the drivers side is behind the exhaust which added to time to the task.
If the line isn't broke or have a hole worn through it you should be able to disconnect it at the drivers side and blow air through it. The oil comes from the oil distribution block.
Good luck
Dave
