Air lock?

[Gup holland]

I am rebuilding my A65 '63 engine Again after 30 years now. All is new, bearings SRM pump, oprv the hole lot. Few weeks back filled the oiltank, new hoses and so on.
When I was spinning the crank by hand via the conrods, I had a good oil return to the tank and the line to the head. When I removed the OPRV I could not see a drop of oil, even When I was spinning the crank for minits.
I concluded there was no oil feed down the pump. I checked frist the oil flow from the tank, this was good. Emptied the tank and checked the piller, this was fully open. Saw what oil in the hose. I took my hand oilpump and squirt it in the hose under pressure. Then When I spinned the crank I saw the level go down and put Some more oil in the hose, several times till I got oil in the OPRV.
Put the hose back on the oiltank and filled with oil again.
Clossed the valve and put the sensor on en filled the hose to the oil gauge.
Then When I spinned the crank by hand , When it build Some pressure I heard air  Come out of the conrod bearings so the sludge trap was full of oil.
Immidiatly  I saw the pressure on the gauge come up to 15/20 PSI When spinning by hand so I new I was not going to be in trouble about the oil pressure anymore.

The '63 engine didn't had a oil pressure switch, the former owner did Made one, only for a switch. Now I have added a oil pressure gauge with it.

I didn't expert that an air airlock could be so hars.