needle tank vent, open or closed during operation?

[Lil Giants]

A couple turns, doesn't have to be a lot, but it does need to vent.

My Fumotec models use a Jung pump with a remotely located reservoir, the supply line to the pump is 6 or 8mm, the pressure line from pump to valve is 4mm. I can't recall, but I think the supply line from the Eagle model is the same 4mm as the pressure line, and they're using an oil reservoir that is much too small for the volume that their pump draws. Even in life sized equipment, the supply line ID is always much bigger than the pressure line, as the pump relies on gravity fed oil supply.