You don't indicate why you were messing with the timing to start with.
Maybe a missing or sheared woodruff key at the crankshaft, the intermediate shaft or the cam shaft. I have also seen an intermediate shaft with a broken keyway as well as timing belts missing teeth, gear teeth full of crud causing the timing belt to slip and idler pulleys with failed bearings causing an out of round rotation. There are a number of possibilities -- take your pick.
If you don't know when the timing belt was last changed you should consider installing a new timing belt and idler pulley. About $40 for parts on line. FR