Check for slop in the timing chain by rotating the engine to TDC without any hesitation, noting the distributor rotor position, and then rotating the engine by hand in the opposite direction to see how many degrees you can move the crankshaft before the rotor starts to move. I hear that 6-10 is within normal tolerance, but certainly am open to differing opinions. This number indicates how far the chain has stretched from its original tightness, when it would take very little back rotation to take up the slack.
Most engines die with their original chain... After 140-150K, depending, some engines with plastic teeth on the cam gear (quieter, doncha know) may turn into shards, and the engine will quit running. Some say a loose timing chain can skip a gear tooth, but that's a LOT of slop.
My $.02.
tom