New Engine Tapping?

i have finally rebuilt my 2.3 SOHC in my 94 grand am. it is up and running but noticed that after running for a little while, less than 5 minutes because it didnt want the tapping to end up destroying something, it was tapping on the top end. i completely rebuilt the bottom end so i know it couldnt be that. so i was wondering what might be the problem? is it a stuck valve or oil might not be getting up to the top? is there a way to stop the tapping or check what be the problem is? i really dont want to drop my engine and auto transaxle to take apart the top end.

i also have the exact same car to a T, blew the head gasket at 163000 miles, we rebuilt the engine, put it in, plugged everything in, started it up, and heard the lifters knocking like no tomorrow, put an ear to the oil pump, and found that the oil pump was junk. check that possibly, i still have a whole car sitting outback that has a trans with only 5,000 miles on it, and a motor with 5 mins on it, my family loves grand ams

i replaced the oil pump and the pump screen when i had the bottom end apart? but i could still be junk i dont know. any other ideas from anybody? i really dont want to have to tear everything apart just to get to the oil pump and replace it again but i will if i have to.

I would measure oil pressure first:
for your engine at 900rpm oil pressure is 15psi minimum
at 2000 rpm 30psi minimum

to me this sounds like rocker arm shaft is not torqued to spec. with just one being loose it sounds like hell. pull the valve cover and take a look

I would agree that this sounds like the rockers or somethings not torqed right causing the tap.

Id check the oil pressure just in case.

how do i measure oil pressure? and i really dont want to have to pull the valve cover off again. theres a lot i have to do that i dont want to in order to get that cover off.