Is it damaging to the motor if my timing chain needs to b replaced

Yes it can. On interference engines the camshaft and crankshaft are timed to open the valves at certain intervals like all engines. What's make interference engines different is that if the timing belt or chain jumps to many teeth either on the camshaft gear or the crankshaft gear it can cause the valves to open to soon and hit the pistons. This would result in bent or broken valves and damaged pistons and possible damage the the cylinder walls. If this were to happen then the engine would need to be replaced, since rebuilding the engine would cost more in parts and labor. Hope this helps.