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:confused: Just a question that doesn't appear in the manuals...I had my heater removed from my GT (1970), and in putting it back in, it looked like the repair manual shows the heat control valve going to the lower heater core tube. I installed the metal OGTS plate, and it's great. I have an electric choke Weber so that eliminates all that extra plumbing. Question is, does the heater hose that runs from the water pump run directly to the upper heater hose tube, and then the lower with the valve run to the nipple on the thermostat housing, or vise versa? It also looks like the hose coming straight back from the thermostat housing must run all the way back around behind the carb, and then down..or can it be shaped like an S to run in front of the carb, then down? Thanks for your help.
 

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on my GT, the heater hose goes directly from the water pump to the lower hose on the heater core, and the other goes from the thermostat housing, through the heater control valve, and then to the upper hose on the heater core. this i believe is right, can't say for certain, it was that way when i got it, so i kept it that way and it seems to work as designed.
 

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Thanks for the info. It makes sense the heater valve would work best in the upper heater hose. Thanks
 

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I think the valve fits better in the upper hose, but I believe that this question has been discussed before (maybe on the ClassicOpels list) and the heater core simply doesn't care which tube is the inlet, and which tube is the outlet.

But come to think of it, the valve probably does, since the direction of flow through the valve probably works best in one direction. So I would go with the valve on the upper heater core tube, which is turn is connected to the thermostat housing. So the coolant flow is from the thermostat housing, through the special right angle rubber hose, to the inlet of the valve, then through the valve (after making a right angle turn; or is that a left angle turn?), through the heater core, and finally back to the water pump suction, where it is pumped back into the block, where it is heated (especially by the head) and exits again at the thermostat. If the heater valve is closed, the coolant just bypasses back to either the radiator (thermostat open) or back to the water pump (thermostat closed).

I think that is right. Any other opinions?
 

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Keith, et. al., I just happen to have the heater core out of my GT, along with almost everything else, and I checked the orientation of the tubes to the heater core. The top tube goes to the upper part of the core and the lower tube comes from the lower area of the core. So think of the heater core as the radiator for the engine, you would want the hotter coolant to enter the top tube, through the heater valve, and the cooler coolant to go to the water pump. Remembering the heater valve is and open or closed valve, it will let the hot water into the core when opened and no flow when it is closed. HTH.
 
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