Mark opted for a Comp Cams' custom grind-232/232 duration, .550/.550-inch lift with 110-degree lobe centers. Mark bases his selection on displacement and expected rpm range. He looks at how high he has to spin the engine to make power and what the customer wants at idle. The 232/232 degrees of duration provides a smoother idle. Mark wants valves on their seats the most minimum amount of time possible in his pursuit of power. He also looks at how quickly valves open and close, known as ramp rate.