Has anyone disassembled a factory hydraulic roller lifter from a vortec? I disassembled two and found only a flat disk inside. Is that all that is inside a stock GM hydraulic lifter? What is the correct way to get the darn thing back together? I put these in the lifter bore and cranked down on a stock pushrod until the cup was below the groove and installed the retaining spring. How does one identify the lift AND duration of an unknown cam? Using a degree wheel? Does anyone have a degree wheel and dial indicater they want to sell? What would be the correct pushrod length for a vortec hydraulic roller cam? Compcams says 7.3.

Not sure about the lifters. The LT1 lifters I've had open had the metering disc.

As for plotting the lift curve of an unknown cam, lacking a CMM with a C-Axis, here's what I've done:



With a handful of lobe lift and degree comparisons, it's fairly easy to get a handle on the lobe profile. LSA, duration on both lobes, and peak lifts are determined, and a little research can often reveal exactly what you have. If you pay a little attention at the transiston from the base to the ramp, you can usually determine if it was intended to be a hydraulic or solid grind.