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3. On the left is the roller cam lobe, on the right the flat tappet lobe. Where the roller cam has a much wider lobe with a more rounded nose, the flat tappet cam has a much narrower lobe with a more pronounced point to its nose. The design of the roller with its smoother ramp rate means the valves open and close quicker and less aggressively, reducing stress on the rest of the valvetrain. The increased area of the roller’s lobe under the lift curve also helps improve mid-range and top end power.