'73 318 timing issue maybe? Really need help

If the timing chain has jumped you will get a different sound when the engine is cranking. When everything is right you get a cyclic sound as each piston comes up on compression. With a jumped timing you won't get the cyclic sound, it stays pretty constant as the engine cranks.

Timing chains typically don't just jump one tooth they jump several and in the case of the nylon coated gear the cam will only turn sporadically. When this happens you won't be building compression because the valves aren't opening and closing at the right time. This cause the dull constant sound when cranking.