Pic attached with added text where I have no hole and 4 hole variant metering valves. Lifters are SpeedPro HT-957.. I've seen posts talk about 4 holes allowing too much oil, but what about the no-hole valves?. It's just a thin disk (maybe .020" thick). I also measured how much room there is for the metering valve to move and its about .035", which was measured by how far the plunger cap protrudes into the plunger vs. how far down the metering valve sits in the plunger. (.180" & .215"). Also note some of the lifters have Lubrite coating (Manganese Phosphate Conversion Coating) aka Parkerized on the lobe side, and the ones that are not Parkerized have a hammer finish on them. It looks like they were trying to achieve better oiling / protection with both the these methods

Edit: Actually the no hole spacing is .035" , the the 4 hole lifer plunger cap sits flush on the metering valve, so no space between the two.

This is for my 400 E block build.

 

I spoke to Joe at Johnson Lifters and although he did not have any old prints, he was able to school me on some of the aspects. He indicated that the "4 hole" metering has been settled on by current manufactures due to the vast majority of lifters they inspected and found the "four hole" to be in the majority That being said, on my later model Federal Mogul / Speedpro lifters Joe explained what limits the oil flow (see pic and explanation).

Referring to the pic, oil flows up through the four holes to the oil well and is restricted by the opening in the "C" shaped protrusion. It then exits out the center hole to the pushrod. It also looks like oil also sneaks past the outside of the metering plate as there is a .0065" plate to wall clearance.

So my question to those who have hydraulic lifter that they had overoiling issues, can you check to see what the innards look like as a comparison to these? The opening in the "C" shape is so tiny (.011 / .024") that the holes in the metering plate become negligible..