The Stovebolt Site Forums The Shop Area Engine Shop Internal pcv?

That canister is a baffle to prevent the oil from directly exiting the valley section of the engine. The idea is to only have fumes drawn out the draft tube. There is a vented oil fill cap on the front of the intake which creates a "flow through" to prevent internal gasses from building up in the engine which can cause problems like leaking seals, etc. Later engines don't use them, instead using a PCV on one rocker cover with a vent to the air cleaner on the other. You can use an alternative but the engine has to have a means to breathe.
Fred