So i just finished my first engine rebuild, I put it all back together in my car and went to start it. It was idling all over the place but besides that, i saw there was a huge oil spill in the rear of the motor, oil filter seems good so i don't know what else it might be, can the pcv black box next to the filter spew out like 1-2 qt of oil?

 

It could if the O-Ring on the oil separator box is damaged/hardened/missing.

 

Double check the oil filter, too.

I once had a brand new Mobile 1 filter leak like a sieve because the o-ring had a burr on it.

Also, check the valve cover gasket. If you didn't put gasket maker in the corners where it goes around the distributor and cam caps, it could leak there. ALthough, that usually cascades down the transmission and the front (cam side) of the engine.

 

2nd that. Jack it up, clean it up, fill it up and check it out.