Yes, if the plumbing and valve is right, if the header is tuned right and if the the outlet is positioned properly in the header, enough negative pressure can occur to suck a lot of moisture/fumes out of the engine. However, we've all seen some attempts which had none of the above. These days, header systems are pretty much po'boy and it's almost as easy to fab and run a pump system.Ive read a few of the post on an evac setup from the valve covers to the exhaust using a kit, can someone explain the main purpose of running an evac setup on a oval track race engine?
A search will find some examples fabbed from old smog pumps.Pump is a better way to go. Can be homemade.
Pump evac systems are a classic case of if some's good, more's better and too much will fry the engine.A vacuum tends to 'dry' the pins of oil and galling can occur.