We discovered these covers give you less room for rocker arm movement than a stock, stamped cover. I have a Sifton 412 cam (which is about the same valve lift as a stock H cam). You could see where the previous owner of these CCE covers had their rocker arms hit. I installed the push rods and turned the motor over with the pan covers on - and didn't hear anything touching. We measured a couple times, and it's gonna be close. Big lift cams might not work with these, unless you use thick gaskets or thin spacers to lift up the covers a bit. Sometimes, 4 eyes, 4 ears and 2 brains are the best . . .