how to fix the 4.0 tick??

[Evan]

2.9Ls have a known oil pressure problem related to widening clearances in the cam bearings. This results in low pressure to the lifters.

4.0Ls have entirely different (roller) lifters, cam, cam bearings, and rockers, but rely on splash lubrication to lubricate the upper end, resulting in spalling. They are also not adjustible.

There's an oil journal that goes directly to the tip of each pushrod on the top. I don't think it's splash lubrication. An example of splash lubrication would be the wristpins on the 4.0 bottom end.