70 Heater Core - Inlet or Outlet?????????

I’m ready to put it all back together and put it back in but since none of it was hooked up when I got the car, how do I know which connection on the heater core connects to the block and which connection connects to the water pump?

Not sure, but does it really matter? It just flows through correct?

Upper is always input, from the pump, simple…

I’ve read so many articles I can’t tell. I just need someone with a 351 Cleveland and no A/C to tell me if their Water pump hose goes to the top hole on the firewall or the bottom. According to some articles the block (hot water) comes into the lowest point on the heater core and flows out the top point. Reasoning was to flush out air. I have no clue. Now I’m more confused cause you said upper is FROM the pump. I thought it was hot water FROM the block and then RETURNS to the water pump.

Im doing the same job on a 70 non a/c

The top hose goes to the water pump and lower hose goes to engine block.

The water pump fills the core via pushing coolant through out the block and filling the core from the bottom.

To bleed the air, leave the water pump connection a little loose and while the engine idles, you will see coolant seeping from the hose then slip it back on and tighten the clamp. Just be careful while the engine is running.

Mrcj001, thank you soooooooooooo much for confirming that for me!!!

Heater core and heater box all redone, new heater hoses, new thermostat and new temp sending unit. Water temp gauge now working. Lower dash and gauges all back in. Pulled her back out of the shop and gave her a good wash after being covered with dirt from the shop for the past 2 weeks.

Looks great Scott! Glad you are making progress :slight_smile: