The carb and engine combo in my sig pulls 17" of vacuum and I was wondering if the stock pcv is not good for this setup. The reason I ask is that the valve seems to be open all the time when the engine is running. Should it be? There is strong vacuum at the valve. When I cover it with my finger there is a noticeable drop in RPM is this normal? I could be mistaken but I was under the understanding that valve was only operational or open when high vacuum is present.

 

The PCV valve is working right. Be sure the other valve cover is vented. The PCV valve should rattle when you shake it.
The engine idle speed slows down when you plug it with your finder, cause less air is getting into the manifold.
Less air= less idle rpm.

If you run the motor without the pcv system, the carb idle circuit will be rich as most street carbs are designed to work with the PCV.

 

Thanks Russ, the other valve cover is vented. I am having a problem getting this Holley adjusted and keeping its settings. One day it will run nice and smooth and on other days its a little rough but not to bad. I am still playing around with the choke on this think again one day its rich and popping through the exhaust next day its fine. I am thinking the choke thermostat isnt working correctly