According to the story, under some conditions, some of the L4 engines cam lobes can suffer prematurewear due to the method of lubricating the area of the rocker arm that bears the load of the cam lobe.

The cam is hollow & has oil pumped into it through the cam supports. It then emerges through holes drilled directly into the cam lobes themselves. The holes are found in three different places on the various lobes & this is said to be the cause of the [alleged] problem.
Some lobes have the hole drilled at 90 degrees to the top of the lobe, on the opening ramp side of the cam lobe. This means that the contact patch gets a shot of oil directly before it bears the load of the cam & this is good.
Other lobes have the hole drilled in the middle of the base circle [from memory], which is 180 degrees from the top of the lobe. This too gives the contact patch a shot of oil before cam lobe contact, but the cam now has to turn an additional 90 degrees before contact occurrs.
The problem lobes have this hole drilled at 90 degrees to the top of the cam like the first group, but on the opposite side to the first ones, which places them on the closing ramp side.
This means that the contact patch gets a shot of oil 'after' the cam has wiped across the contact patch & yet another 90 degrees more of cam rotation untill the cam contacts the patch again.

I have been involved with L20B engines since February 1981 in my work fleet & I still use one in my private 200B hack. I have never experienced this problem, & I have never met anyone who claims to have experienced it, yet early L6 engines seem to have used the spray bar which keeps a constant supply of oil on these contact patches, & this is supposed to be the fix for this [alleged] problem.

Preventing the oil from geting inside the cam is also a part of the modification as this method of lubrication becomes redundant with the spray bar & therefore constitutes just another internal oil leak that drains off precious oil pressure.

So,.. is there actually a problem with L series cam lobe wear? Maybee in race engines with very high valve spring pressures, & if so, then this is supposed to be the fix, but Ddgonzal is right, millions & millions of L series engines have soldiered on for decades all over the world without a hint of a problem.