Hasn't got anything to do with hydraulic. It's the difference between flat tappets either mechanical or hydraulic and ROLLER lifters. flat tappets require break in at fairly high RPM. Roller lifters do not. Find out what you have for a cam and follow exactly the cam manufacturer's instructions. All cam makers have destructions on their websites. Basically, this means varying RPM and keeping RPM above 1800-2K or so for 15 --20 min or more.
