Virgil I have a shelby motor and race 98% of the time. The best way I found is to install a PCV valve in the right side of the motor and a breather in the l/s valve cover. No leaks in 15 years. I did in year 16 blow a small piece of cork valve cover gasket out and have a small
oil fire. No damage to car. My fault for running the same gaskets for so many years. You could be building up too much pressure in the motor. The rebuilt motor hasn't sealed in the new rings yet. Rick L.