On my 151 engine and the A2 engine there were 2 types of inlet screens,the one with no rubber was on the 151 and the A2 had the one with the rubber.When the oil pan gets installed the rubber gets folded over about 3/4 up, with a little gap.So why did this have the 2nd hole with the rubber?
By the way,for the last month or so I had a no oil pressure on the 151(was driving it with 35#,then it went to zero)put pressure tester on sending unit,etc no reading
put new oil pump on,still no pressure,plastigauge the rods&main bearings they were at .002--.003",Took it to a machine shop,he said main bearings were worn(he arrived at this conclusion by shooting air in block hole,then noticing air shooting out of center main bearing.So it sat for about a week.So I took it as to me he wasn't much interested in solving the problem.So at home,with the oil installed in engine/no cam shaft installed I would turn the oil pump with impact gun,no oil would shoot out of holes in the block where the filter bracket bolted to block.So to me the screen inlet tube/screen had to be plugged(but it wasn't as I could blow air thru it,run water thru it.So I took the inlet screen tube from the A2 engine and put on the oil pump,but then I couldn't get the oil pan installed so I took the A2 pan,and that went on.Put oil in it,turned the oil pump, had oil shooting out 3,4 feet.Put oil pressure tester in sending unit hole,got 10 lbs of pressure.Wow!! now I got pressure.I then looked at original oil pan,the bottom had been dented in,so the only thing I can figure is the oil pan went up against the inlet hole so that keep the oil out,maybe the blow also put a crack in the tube flange too,Also maybe the dent was there when I bought the mutt as I never hit anything and now somehow conditions were right so the no oil pressure shows up.I don't know, but I do know I now have oil pressure.So now I am wondering should I grind he valves? Put new valve seals in it( it smokes when starting up) This 151 run pretty good before the incident.