Nissan Repair: 91 Nissan hardbody broken camshaft, valve damage, overhead cam

Question
I have a 1991 Nissan hardbody truck with the 4 cyl.  with the ka24e engine with an overhead cam. it broke down on me and i had it looked at and found out the camshaft is broken it is cracked at the front end where the timing gear connects and the timing gear is also damaged the chain didn't jump off . the way it broke just caused the gear to spin freely. it has always been a good tight motor never used a drop of oil between changes.any way my friend suggests i can replace the top end of the motor and seems to think it should be fine. do you agree. Why would the cam just break? do you think there is possibly more damage than that. he also said that all of the valves were up which he said was a good thing.
thanks
Michele

Answer
Michele,

If the timing did not jump and the cam just had a casting issue them it would just be a matter of taking the head off and getting it worked and the cam replaced.  When the head is off you will see if you have any valve damage to the pistons.  Otherwise it should be fine.