I've had a replacement block but the sprocket ,oil pump and spacer under the pump is from the old 1.9 block ( ive no idea what the block was off but guessing a 1.6  which shouldn't make any difference  but there is literally no slack at all infact the chain is in tension and the oil pickup side of the pump wont sit down by itself unless pushed down  . New or old chain makes no difference . I had another crank sprocket but its way bigger and must have came with the spare block and no way it will fit . Should I leave the spacer out  ? any advice appreciated as I haven't heard of anybody else with too tight a chain its usually too slack if anything .       I didn't measure the spacer yet but its less than 1mm id think and came of my old engine . The number on it is 1A . give the new block maybe had the bigger crank sprocket so mush have had a smaller oil pump sprocket etc , the crank sprocket is a 2 piece whereas the one I've now is one piece compete with oil seal running bush all in one. My old engine block was a 1991 1..9 .