I made a new version of a valve cover for setting hydraulic lifter preload with the engine running. This version allows for the adjustment to be done with the engine idling at 900 RPM which is normal for my engine when fully up to temperature. There is almost no oil mess with this design. The holes in the valve cover are 1.25" and line up exactly with each of the poly locks. The plugs for the holes are silicone rubber and make a complete seal.