When I installed gt40 heads and headers etc on my truck I moved the stock air box from over the driver's side head to the fender . I used air intake tubes that go from the air box to throttle body from a 90's f150 and part of the original air intake pipe to make a fresh air intake next to the radiator .

I had to use aftermarket valve covers to clear my 1:7 cobra rockers and I could not use the factory twist on oil filler and vent . i used an aftermarket one that has a filter built in .I am wondering if i should still use the stock filter in the air box ? Any reason not having the filter in the air box would cause issues ? Otherwise I'll block that off while i'm working on the mount for the air box .

 

Performance wise it doesn't matter. The PCV is pulling air/gases out of the crankcase and fresh air needs to get in there. Whether that fresh air comes from the air box hosing or a separate breather on the valve cover doesn't matter. The only downside to the separate breather is that you have to clean it every so often.

 

Thank you .