heater hose on a/c truck

[incoma]

I've forgotten and don't have any "before" pictures of this particular item. I'm connecting my heater shutoff valve in my heater hose running from the intake to heater core. Which direction does the water flow? The valve has an arrow on it, but I'm not sure which way to install it.

If I can get this one last piece figured out, I can fire my beast up. Help!!

I've attached a pic for reference..which way should the arrow point - to the intake or to the heater core.

[Stocker]

That is different than on my '72. What year, what engine do you have?

[JimKshortstep4x4]

The heater hoses are different sizes. The smaller one, (5/8") connects to the bottom of the heater and the flow on the smaller hose is toward the heater.
The larger hose (3/4") hose is the return hose and flows back to the radiator, (or the water pump if you prefer).

Depending on the size of the nipples the shut off valve should be installed in the hose that fits in the direction of flow.

Jim

[incoma]

Thanks. That's what I needed. My valve fits in the 5/8" line, so I'll point the arrow away from the engine and towards the heater core.

For reference, I've got a 1970 GMC pickup with a V8 engine.