I'm having a problem I just did a engine swap.

Yeah the head that I took out of the other car worked perfectly fine. I did the timing n everything on it put the key in turned it a little bit to make sure everything was working correctly before I tried starting it sounded like the belt slipped a little bit so I got out check and it did so I was getting ready to re adjust it and noticed the intake manifold side cam wasn't spinning counterclockwise as smoothly as the header side can was spinning which made the belt skip a tooth on the intake manifold side cause the cam gear did not move but the crank and header cam water pump timing belt tensioner was all working fine just that 1 cam isn't spinning it does but not good it takes a muscle to spin it everything on the engines pretty much new I have a b20 block and a b16 head all the work fun it's just that cam. It's never been started donor car was perfectly fine any ideas

I don't get what it could be I took the valve cover off and checked in there and everything looks like it's in there right And nothing blocking it from spinning it's my only car :-( and it's been off the road for 3 months