The heater core has 2 tubes sticking out of the firewall. That said, which one goes to which hose??? OR does it matter. There is a hose from the head, and a hose spliced off the bottom ratiator hose. Thanks

Justin,

If you have new rigid hoses, they will only fit on one way. The opposite way the hoses dont line up and go through the holes in the firewall. At least that is the way that my '73 worked.

On a 240Z, the hose from the head is the lower hose. Not certain if 260/280Zs are the same, but I suspect they may be.

I have a l28 in it, and I made the heater hoses from a spool of hose. Thanks for the info, i'll give that a shot when I get out of school.

On my 78 280Z, the hose from the head is the upper hose.

Notice on Stephen's picture a couple of directional flow arrows.

If you go inside, you'll see that the hose with the arrow flowing INTO the car is the one that goes to the HC Valve. That is so you can regulate the amount of heated water you release into the core to then transfer heat to the air being circulated around it.

If you were to connect it the other way around, the core would constantly receive the FULL amount of hot water from the engine and you would be regulating only the amount of RETURN. If you were to connect it this way, even with the HCV at full close you would still feel heat coming from the heater core, due to the convection of heat through the water.

2¢

E