I have oil leaking from my oil filler cap. I have recently changed the head gaskit, cleaned the valve train and put in new valve seals. I did a compression test and got very even numbers. I also don't burn any oil. I have also removed my cats and smog pump and closed off the Y-Pipe joining the ports at the back of each head by the fire wall. Could this be the cause?

Any ideas why this is happening?
Also, what purpose do the two lines from the valve covers serve?

Thanks guys! in advance.

 

check your pcv valve, the crank case pressures are too high, causing it to blow out the oil under the cap.