Mopar Performance Purple Mechanical Camshaft - P4120653AE Cam Card

rumblefish360 said

This ^^^^


Not exactly true but …..
Most calculations are done with a know advertised lift point of let’s just say @ .006. If you start running through a Comp Cam catalog, only certain cams are advertised in this way while others are at different points.
Now travel onto Crane Cams, Howard’s, etc….
You’ll find the same thing.

Click to expand...

I disagree. I think it doesn't matter where manufacturer, "X", wants to start measuring duration. If they give you a recommended installed lobe centerline spec and a duration spec you can derive the events for whatever their particular method for measuring is, as long as the opening lobe profile and closing lobe profile are mirror images of each other(symmetrical about the lobe centerline).