>>>*All the spring does is control the bypass, it opens when pressure gets excessive?

The HV pumps have slightly redesigned internals that allow about 4% more volume and this does affect pressure but not a lot. On an engine in good shape, or unless the engine is used for competition or severe service, the HV is not needed.

Typically when we see low oil pressure on these engines, we suspect main bearing clearence. If reading zero, we start looking for a galley plug missing....*EB

*Beats the he** outa me!....*LOL**...