splain the difference
basically solid roller is for track cars...a lot more duration cam's...you can spin a lot higher safely...but you have to set lash every so often...
hydraulic cam: a cam using lifters that has a valve-controlled plunger inside its body, preloading the pushrod at the closed valve position through oil pressure lift: distance the valve is depressed from its seat when closed to the peak valve lift when open fully
mechanical (solid) cam: a cam using lifters with only a radiused contact face in which the pushrod end sits without internal valves or other complexity; requires periodic lash setting


