Eric's cam challenge

Agree that seat timing matters, but when the adv duration varies so much between different manufacturers, & even within the same manufacturer, how does that provide useful info for picking a cam? See the Pontiac & Chrys cam, below, top row. I believe it was Crane who introduced the 050 measuring point as he believed that the duration at that lift gave a useful indication of the power range for profile. The others followed....

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It's pretty simple really. Comparing seat to seat to .050" allows you to see how fast a rate a given lobe is.