The lifter is filled at zero spring pressure, when the valve is on it's seat, and the valve train is only loaded by the internal spring in the lifter.
Hi spring pressure/ lifter bleed down is a separate issue.
Clearance is there for a number of reasons, including too little clearance, but I still don't think it could be worn that bad ( within reason) that it would bleed off so much oil that the lifter would starve. You would think if that's the case, then all the lifters further down the line would also be starving.
More likely, the oil is just going into the lifter and getting squirted right back out again.
Funny how it went from pre priming a lifter to not doing it before assembly..I wonder what changed...
