Craigvining

I have a 97 Civic v-tech. I bought for a dirt track car. We took the head off and reseated the valves cleaned the head and put on a new timing belt. Within a couple of seconds of trying to crank I heard a snap. It was the ears on the cam shaft that the distributor seat into. It sheared both ears off the cam. When we took the lifters back off I noticed that the cam had slid toward the timing belt so that the ears of the distributor would not have been completely seated, but i dont think that was enough to shear the cam. There shouldn't be any pressure there, certainly not enough to do that damage, Should there? Any suggestions?