What is the difference between a flat tappet and a roller camshaft?

Flat Tappet vs. Roller Camshafts

Camshafts are classified by the type of lifter they use. The lobes on the cam are machined differently based on the intended lifter. Lifters are sometimes called a "follower" or "tappet." They contact the cam lobe with either a flat surface or a wheel.

Flat Tappet Camshafts

In reality, flat tappet lifters are not flat. They actually have a slight crown on the face. The camshaft lobe is machined with a slight taper. This causes the lifter to spin as it rides on the lobe. It ensures even wear on the two surfaces.

Flat Tappet Cams are widely used and perform very well. They are also much more affordable than a roller cam.

When changing cams, the flat tappet lifters will need replaced. Follow this link for details on Replacing Lifters.

Roller Camshafts

Roller lifters feature a wheel supported by needle bearings and an axle. This wheel is attached to the bottom of the lifter body. The lobes of roller camshafts are machined perfectly flat. Roller lifters are linked together, or anchored somehow, to prevent them from spinning.

Roller Cams minimize friction. This provides more power. It also wears less, which leads to a longer life. Roller cams also allow for steeper lobes. In other words, they allow for more "area under the curve." This means the valve opens faster and remains at a higher lift for a longer period of time. This allows for more airflow and more power.

When changing cams, roller lifters can be re‑used. Follow this link for details on Reusing Lifters.