Aggressive cams require heavy duty springs to keep the lifter from bouncing on the cam. The more open pressure than a stock spring, you risk punching the push rod through the seat of the stamped steel stock rocker arm. So you have to figure out your cam/spring combination and I’m not saying stock rocker arms are bad, they oil awesome and are light as all get out. They just are not going to stand up to stiff springs and .6 lift cams. No way about it you change heads you have to check push rod length.
