64 - No heat

[chris1044]

I've been lurking for sometime...finally picked up a 64. It's a 20 footer, which means I'm not afraid to use it right up to the point of salt on the roads here in MI.

I've been having some issues with the heat - as in there is none. The truck has the thrift heater in it, engine is a 350 with a high performance Edelbrock water pump - for those not familiar, it's the style that has NO provisions on it for any heater hose. As a result, I've got one hose that feeds the core from the port on the intake manifold, and another that is plumbed just up stream of the thermostat housing - between the engine and radiator inlet. The blower/blend door works fine and I get plenty of airflow over the core then into the cab.

I don't seem to be getting any coolant flow through the core, so today I pulled the hoses and blew through it via the air compressor. This is where my questions starts:

1) Does it really matter which hose is in and out? One's a 5/8" ID and the other a 3/4" - right now I believe the 3/4" is the inlet and the 5/8" the outlet.

2) My core had a plastic restriction orifice in the smaller 5/8" tube. Why? I pulled it in hopes of getting increased flow with it out....no success.

After fully bleeding the air from the system today, I'm once again left with a semi-warm hose from the intake and a cold one going from the core return. I know the core isn't plugged, so there's got to be too much head to flow through it on the return side.

I'm fairly sure I can plug the T-Stat housing port and just dump the core return back into the top of the radiator as there's another plug there. But why would there be a restriction valve in the core? Other suggestions?