The four cylinder AMC engine is pretty much the same as the inline 6, minus two cylinders. They share quite a bit of the same components, so I would say that the timing chain will wear about the same as the 6 cylinder. But even the 6 should have it changed out periodically. Just remember it is a lot cheaper to replace the chain than to have it break and have to replace the head, pistons, etc.
Is the jeep AMC inline 4 have a timing chain that never needs changing like the 6??
Timing chains need to be changed, just not as often as belts. They will wear out eventualy.
