Timing out?

I just did a timing chain on on my car, changed water pump, oil pump, thermostat, new belts, chains, tensioners, sprockets. I put it all back together and it cranks slow n a noise as if a chain is loose plus when is cracking sounds like a low backfire. I aligned all timing marks on the chains but not sure on crankshaft n one side of both side chains felt really loose! Help how to set timing now that is really out of timing?