Hi, I have recently done a complete rebuild on my engine. And it didnt go as smooth as I thought it would, when i start up the engine it seems to take about 5 - 10 seconds before it builds up any oil pressure which can not be a good sign ? When the engine is cold the oil pressure is around 80 psi @ 1000rpm idle. When the engine is warmed up the pressure sinks to around 15 psi which is way to low considering the lifters starts tapping :S But when I drive I think it seems to be ok, with 60 psi @ 2000 rpm give or take. Does anybody have any idea on what I could check before I start removing out the engine again ?

The engine is an sierra cosworth 4x4 (200) engine.

Every advice will be appreciated...