Mustangs Monthly and Fast Fords had an excellent article on cam basics about 3 months back. Duration is the time the valve remains open, @.050 is just a notation indicating (pretty much standard) where the measurement is taken from. More lift allows the valve to travel futher down from the valve seat (valve closed means it is against/in the seat). This allows more are to clear past any obstruction that the back face of valve may create. You do not wish to go the bigger is better route when looking for a cam. Many factors are applicable in this situation. Are you a NA car or power adder, if so you would wish to have a longer duration on the exhaust valve to allow for increased velocity and amount of the gasses to exit the engine and spool up the turbo and dump that added compressed volume in the cylinder. If you go to big and too wild you will suffer a stumbling idle, which in effect leads to daily driver headaches. Your best bet is to contact any of the cam manufactures and ask them to specify a grind for your particular application. As always, perform more research if you are wanting to make the selection yourself.
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