Help!! Oil pressure problems
I have an 83 Full size Bronco. I have rebuilt the 351W. After I bolted in the engine, I started it up and the lifters where knocking like crazy. I let the engine run for a few minutes as I thought maybe the lifters needed to "fill up". Then I shut it off (no pressure gaugue only the idiot light on the dash, registered low) and pulled a valve cover to see if any oil was evident into the top of the heads. When I started it again, there was no oil present, and I oiled the rocker arms with a oil can and they quieted right down. So I pulled the oil sending unit sensor off of the adapter and lo and behold oil came out of it when I started it back up. I put a new oil pump in the block and tested the oil pump prior to installation and it worked, soaked the lifters overnight before installing them, and have no idea as to what is going on now! The oil on the dipstick was aerated, lots of little bubbles present.
My questions are as follows:
1) How long should it take the oil pump to supply lubricant through the whole block upon initial start up?
One auto parts guy has told me that he has had to run engines upwards of 10 minutes or so to initially "pressurize" everything. I thought that was excessive and do not want to risk damage to the engine attempting this.
2) what would be the most logical way to troubleshoot this problem?
I have thought about mounting a gauge off of the adapter to check the pressure level at the sending unit but do not know how to check the pressure levels through the top of the engine. The only things I have guessed about are the following:
Cam bearings not installed properly, (Hope not had a machine shop do this).
Crankshaft bearing gallery holes not lined up. (Don't think so though was pretty careful checking those during reassembly).
Internal freeze plug blown out?
Block cracked? (Had the block hot tanked and magnafluxed, don't think so).
Bottom line is I would like to figure this out before I go through the hassle of pulling the engine back out and starting from scratch. Any ideas would be greatly appreciated, thanks in advance.