The lash specification can be anything the cam grinder wants it to be. The "acceleration ramp" is an area of slow, gradual lift designed to stack all the valve train parts together solidly before the lobe actually starts lifting the valve off the seat at a much faster rate. The same holds true on closing, with a quick deceleration to almost closed, then a gentle drop onto the seat to prevent battering the valve and a further slow drop to reestablish the lash.

It's possible to "map" a cam with a dial indicator and a degree wheel, and discover the lash settings, even if no specifications are available. I do it with race cams all the time.
Jerry

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