Timing issue

I recently replaced timing belt/water pump in my car. The water pump had a hole in it and I figured I should change the belt while I am at it. The timing mark on the back cam was slightly off counterclockwise before installation of new belt and car was running smooth. I initially did not have the cams locked down and the rear cam slipped as I was putting the belt on. This engine is a non-freewheeling design so I had to loosen the rocker arms and I adjusted the cam back to the timing mark. After installation and rotating crank twice everything still seemed lined up. I started the car today and it seemed to run a little rough. I drove it up the street and began to hear a knocking noise and then my engine stalled and would not start back up. So I am assuming it jumped a tooth? Is there a trick to setting the timing on this engine?