need Help! rebuilt engine knocking

Hopefully somone here can help me with this. I just rebuilt my first engine on my 89 probe gt, dropped it in hooked it up and it is making a terrible knocking sound. Other than the knock it runs fine. I checked the spark timing and valve timing and as far as i can tell they are fine. I have no idea what the problem is and my mechanical expertise is limited so any input would be appreciated.

Was the knock comming from the bottom of the engine? You should have taken a long skinny screw driver against your ear and did point check searches to locate the knock before you removed the engine.. Chances are if it was a bottom end knock, you installed the wrong crank or rod bearing(s). If you don't own dial calipers or micrometers, always use plastic guage to measure clearances on crank mains and rod bearings when rebuilding engines.
Good luck.
:)

Did you prime the oil pump before it was started?

That would do it too! I've seen that happen many times.
:)

The engine is still in the car. Im not sure what you mean by prime the pump. I did lube everything up and cranked the engine for about 20 seconds without the engine fuse in before i started it up. Used plastiguage and had the crank inspected by a machine shop. As far as i can tell it sounds like the knock is coming from the head, but it is a rebuilt head and the cam is also new so i am confused as can be about what the cause is. The knock sounds a lot worse than any lifter tapping i ve ever heard on one of these cars, is barely audible at idle but if you press accelerator it is very loud. I don't have any reservations about tearing this mother apart again, i am just worried i will make the same mistake and have the same results.

Well now we have some more info, have you checked the ignition timing? If its too advanced it can cause this problem. Have you pulled the spark plugs to see if one may be contacting the piston? Wrong plug with too long of a reach? Is there a sticky valve hitting the piston?
Pull the valve cover and inspect it while the engine is turning over. If these don't show anything then the next step is pulling the cylander head back off and inspecting for metal to metal contact. If the machine shop milled the cylander heads maybe they removed too much metal and the clearances are bad.
Good luck.

Got to inspecting the engine today and what i think is the knock sensor, on oil pan on the passenger compartment side, is not even hooked up. I know i am an idiot so no need for anyone to tell me this. Does anyone know what it hooks into as far as which harness goes or color coding on the wires. I am pretty sure this could cause the knocking i am getting. any info would help.

It could cause the problem yes and you never said the engine light was on.. this would have given a better clue. Usually the computer will advance the timing until it receives a signal from the knock sensor, if no signal then the engine light comes on. Look around the area of the sensor, you will find the connector.
Good luck.

decided today to just sell the car i will post in a new thread. Just thought I would put this up here in case anyone would be interested