Getting close to starting my engine and just have the orange valve covers on a 283. I would like to buy some aluminum ones. But here is the question that I have. Why are there so many holes in the covers I have seen covers that have two holes in each one. I will have my pcv valve hooked up to the blow by vent in the back of the motor, there is an adapter there now to connect a hose too. I will connect it to the base of the carb. And there is the vent tub in the front of the motor to put oil in your motor. So why do I need to have holes in my valve covers.

Thanks again for the help
Rocky