I found out the hard way that not using a baffle under the vacuum fitting on my new motor caused a lot more oil being sucked into the tank on every run, it would fill the tank up in less than 6 runs
I swap the old valve covers onto the new motor and cure that problem
Using the baffle under the fitting resulted in almost pure moisture with in the tank and very little oil
I think the oil droplets being slung off of the rocker arms are being forced into the fitting and up the hose under suction and not being given a chance to drop back into the heads, the baffle stops that