As I recall it's around .285"....that's one reason these motors respond so well to even a drop in cam. The OEM units don't even approach the convergence lift of the stock valves.
According to Megacycle Cams, the Z-1 stock intake cams have .327" of lift and 237 degrees of duration (@ 0.040") while the stock exhaust cams have .296" of lift and 229 degrees of duration (@ 0.040").
