Valve Spring Pressure - BBC stocker

[nhramnl]

Originally Posted by Tom Broome

Hard to loft an intake valve on opening, it's only moved the tappet .100 or so. Now over the nose....okay, but the piston is long gone by that time. Possibly a big bounce off seat? Pushrods might change things
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Not disagreeing with what you're saying, but if the opening ramp of the intake lobe is too close to "instantly vertical" (like what roller cam guys are using these days) the lifter can actually try to dig into the lobe and create milliseconds of valve train slack (shudder), which can cause things like valve spring surge. Even the roller cam guys admit that there is only so far you can go with "snapping" the valve open and closed.