Knowing the terminology of camshafts can help you understand how it works.
- Base Circle: The back side of the cam lobe.
- This is the area of the lobe where the valve is closed.
- It does not provide lift.
- Also known as the "heel."
- Clearance Ramp: The transition area between the ramp and the base circle.
- This part of the lobe takes up the lash in a solid valvetrain.
- Also called the "lash ramp."
- Opening Ramp: The side of the lobe that raises the lifter.
- Lobe Centerline: The highest point of lift on the lobe.
- Centerlines are listed as degrees of crankshaft rotation.
- The intake centerline is After Top Dead Center (ATDC).
- The exhaust centerline is Before Top Dead Center (BTDC).
- Nose: The top part of the lobe.
- This is where the valve is held open as it transitions from opening to closing.
- Closing Ramp: The side of the lobe that lowers the lifter.
- Ramps: These control the raising and lowering of the lifter (clearance, closing, and opening).
- Also called "flanks."
