A kinetically unyielding, statically compliant (KUSC) positive return valve action. In one embodiment, a guide is pivotally mounted and rotationally abuts a limiting bench. A pin mounted slidably on the guide is linked to a poppet valve, a driver positioning the pin along the guide. With the valve seated and the driver overtraveled a deflection opens up between the guide and the limiting bench that resolves the overtravel, which deflection is opposed by a forcing spring. As the valve is initially lifted, valve-lift kinetic force is buttressed against the guide mount and the limiting bench, neither of which yields. With increasing lift the pin position passes the guide mount axis to be cantilevered on the guide at maximal valve lift against valve-return kinetic force: this also is unyieldingly buttressed. The action is adjusted by positioning the limiting bench either manually or by hydraulic lash adjuster.