I built a mild 360 hydraulic cam 273 adjustable rockers. I used Johnson US made lifters. Since new (600 miles) I get a pretty good tap tap tap. It will almost go completely silent after 3-4 minutes. I have tried all preload settings. It's just a lazy lifter. I pulled the lifter and took it apart. Seemed clean and normal. It's not wiping the cam.... knock on wood. I have a new lifter I am going to throw in and break in. Has anybody else just had a lifter than wouldn't pump correctly? Thanks.