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A couple of points.
1) - There is no way that the engineer who designed the original cam shape 'meant' for the valve to travel in the theoretical 'blue' curve you depicted in the first picture. That would mean they just didn't know that the lifter would interact in that way with the lobe, and I'm absolutely sure that tidbit did not escape them. They designed the lobe for the end result - at the valve tip - even including the rocker arm's contributions. If they had been using roller lifters they would have designed the shape of the lobe differently - to produce what they thought was the best end result at the valve.
2) 'Optimal' valve actuation isn't as simple as maximizing the area under the curve. Opening valves faster and farther doesn't always keep on adding HP. Air isn't electricity, it doesn't immediately stop and start, especially at the speeds at which things are happening at 6000 rpm. Snapping an exhaust valve shut abruptly at the end of an intake cyce could cause more reverberation back out the intake than would closing it more gently. Snapping an exhaust open quickly at the beginning of an exhaust cycle could yank the air in the port backwards momentarily. Valves have inertia and momentum too, snapping them open faster and farther isn't very easy on them when the valve needs to open and close again in less than a hundredth of a second.
This isn't to say that the cam lobes they developed back in the 60's are the best that can ever be done, just saying that they probably aren't *that* far off.
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I'm JohnMc, and I approved this message.
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