I had a heater water valve on my 67 camaro when i bought it and when it turned the heater on i wouldnt get any heat. But it had a vacuum hose running to it from somewher so i took everything apart and coolant drained out of the heater core but the guy told me it was bad but why would there be coolant in there?? should i still just change it and if so how do i do it?

The water will have water on both sides at all times. Purpose of the water valve is to turn off coolant flow through the heater core when AC is selected so the AC isn't cooling the hot air.

Under normal conditions, all heater hoses will be hot to the touch, the water valve defaults to the open position, coolant flows. Select AC, the valve closes.

So if the hoses are hot to the touch, valve is open. If you have no hot air inside, then the air door is not doing its job or, the cable is broken, the control lever is broken, or the cable clip to door is missing.