Dry sump venting open or closed.

[4pipes]

I run a system with an Aviaid Dry Sump system on a stroked alloy 427. Used to have several small leaks, one probably was the rear main side seals and one at the distributor. These engines can develop quite a lot of crankcase pressure.

I sealed the engine and used a calibrated vacuum leak on the manifold, so that at idle I get around 2-3 inches of vacuum. I still vent the dry sump tank.

I used a regulator from Peterson:
http://www.petersonfluidsys.com/engine_breath.html

No more leaks! Love it.