Original C9 Used Camshaft 242-0673 For Excavator E330D E336D

C9 Used Camshaft 242 - 0673 For Excavator E330D E336D Original

Specification

Description

What does duration of camshaft mean?

Camshaft duration is the period of time, measured in degrees of crankshaft rotation, that a valve is open. “Advertised duration” measures duration from the point where the cam manufacturer believes the lobe starts raising the lifter. This is called the checking height and it varies from manufacturer to manufacturer.

Design

Base Circle

The base circle is the round portion of the cam lobe where the valve lash adjustments are made. A slight high spot on the base circle is called base circle runout.

Cam Lift

This is the maximum distance that the cam lobe pushes the lifter. Because the rocker arm ratio will multiply the overall valve lift, this should not to be confused with valve lift.

Cam Profile

The cam profile is the actual shape of the camshaft lobe. A flat tappet camshaft is slightly more pointed on the nose of the lobe, while a roller lift camshaft has a more rounded profile on the nose of the lobe.

Degreeing the Camshaft

This is a process that synchronizes the camshaft with the crankshaft. For best engine performance, builders use a degree wheel to dial in this measurement. Most manufacturers will list the exact specifications for each cam on the cam card.

Duration

The length of time the valve is held off the valve seat from the cam lobe. This is measured in degrees of crankshaft rotation.

Duration at .050-inch Lift

This is the distance measured in degrees of crankshaft rotation from when the valve is open at .050-inches until it’s .050-inches from closing.

Gross Lift (Valve Lift)

Typically camshaft manufacturers list this measurement by multiplying the cam lobe lift by the stock rocker arm ratio, usually 1.5:1. For example, if your cam lobe lift is .319 and you're using a 1.5:1 rocker arm ratio, you can take .319 x 1.5, which is .479 inches of overall valve lift.

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