What could cause this? 360 problems ####update####

If the cam is still installed you can do a quick-check without taking the front off.
1) roll the crank around until # 6 piston is at TDC and on what would be it's compression stroke. You can tell this by the fact that the lifters do not move when you shuttle the crank back and forth. If this is not the case, then the cam is NOT in right; go to step 4.
2) Go to the #1 piston. Lay a straight-edge across the lifters. Shuttle the crank a few degrees either way until the straightedge contacts each of the two lifters in at least two places. The straightedge should be about parallel to the deck. Now read the degrees on the timing tab, relative to the TDC mark on the balancer.
3) Assuming the TDC mark is correct, it should be within about 4 degrees of TDC on the timing tab, and the piston should be within a few thousands of the deck, or at least from TDC. If this is not the case, then the cam is NOT in right; go to step 4.
4) Now you are justified in pulling the front off. When you get there,
Make sure the cam-key is installed and the Bolt is torqued properly