Crane Cams also supplied these 1.550-inch diameter Pacalloy springs. Normally utilized in big-block applications, these springs provide 230 pounds of seat pressure and 600 pounds of open pressure. Spring pressures of this magnitude would collapse a hydraulic lifter. Solid roller cams require increased valvespring pressures to keep the lifter in contact with the camshaft lobes at all times, thereby preventing valve float. It's important to note that these springs are not a drop-in replacement for the small diameter stockers. ARE milled the spring seats on the heads to accept the big Cranes.