Just finished bolting up the last parts to finish my PI head swap. I have all electrical power, starter turns, crank and belt is turning but not really sounding like it is trying to turn over. Mechanical oil pressure gauge is at 0 psi. Oil pan is full, unscrewed filter and filled it with oil as well. Plugs and coil packs are routed correctly (double checked). Any ideas on how to attack this problem? How long should I have to crank the engine before the air is out of the oil line and pressure returns?