It sounds like the lifter is bottomed out from over cutting the valve seat or not trimming the top of the valve stem correctly. You can check this by depressing the bleeding the lifter all the way. Put the lifter and rocker arm back in. Rotate the base circle of the cam love over the rocker arm. Basically you are at zero lift. Getting To The Bottom of Hydraulic Lifter Preload By Engine Builder on Jun 17, 2011 Hydraulic lifters have been the choice of the automotive industry for many years for several good reasons. When compared to a mechanical lifter, the hydraulics are: 1. Quieter. 2. Low maintenance. 3. Able to adjust for thermal expansion of the engine. 4. Others work better with a heavy pre-load because oil volume is reduced under the plunger, which increases stiffness. COMP Cams® Short Travel Hydraulic Roller Lifters allow you to have the advantages of both light pre-load and reduced oil volume, producing the most stable and highest revving hydraulic lifter available.