Z24 timing chain

I recently replaced a water pump in my z24 cav along withe tensioner. Now there is slack between the two cams and I can't figure out why . the tensioner was replaced correctly and so was the water pump, Help!!

when you replace the water pump you are suppose to replace the timing chain to so you can prevent that problem

Is it possible that the timing chain stretched, i have never heard of that happening before
Also, why would it prevent any problems if it was fine before the water pump installation. Is it possible that i bought a water pump that is wrong one?

when you replace the water pump you are suppose to replace the timing chain to so you can prevent that problem

i thought the same thing but i was told at a shop that you only need to change timing belts when changing the water pump... not chains.. but just what i was told, who knows.