[fast924S]

There is very little vaccum in the crank case. The reason the valve is connected to the intake is because of emissions, any crank case vapors are burned not dumped into the outside air. The manifold does put some vaccum on it just to suck the gasses out. If there was a large vaccum then you would be blowing out seals and have problems with your rings. If there was no vaccum and a Positive pressure you will also blow out seals. The best it to try to make it neutral and let it vent like the pcv lets it. Let me know what else I can help you with.