GSR timming Belt on straight LS?

I rebuilt my LS recently(with an LS head), put 96 up oil pump and a B18C water pump. The B18A/B water pump has 19 teeths and the B18C has 22 teeths so with an LS /Vtec setup, you take the timming belt in function of the water pump. So I take a B18C to match my B18C water pump. Result my timming belt is too loose even with the tensioner in max position. Its not an OEM timming belt so I just want to know if anyone have seen this before.
If someone know if vtec and non-vtec head have not the same height?

Its not the head height rather the block. the more cc the taller the block and vtec water pump size.