A Road Draft Tube?

[sir_talk_alot]

so i bought a 283 block and crank from a guy the other day(got a flame to my butt cuz i thought it would be cool for a future truck, or ratrod, now i realized ive clogged the garage and now its on craigslist), and was confused as to what the heck a black canister was doing in the lifter galley. he said it was a primitive pcv valve. someone want to explain to me whats so great about it? he said they are desired by people with old engines....i just figured it was just like a pcv valve, it just vented the internals....am i right?