The OP did say he primed it before starting. I find if it is on an engine stand, turn it 45° to get one bank level. Put a couple of squirts from an oil can in those 4 cylinders. Turn it over to distribuye oil on the cylinders and rings. Put the plugs back in and let it sit a day. Rotate the engine 90° and do the dame to the other 4 cylinders. Rotate back to level after another day. Easy access to prime the engine on the stand by spinning the oil pump with a drill. Remove Rocker covers first to verify oil up top.