I have a brand new heater core, brand new cable/vacuum valve and brand new water pump and the FE motor runs warm but not overheating even in traffic in the summer. I cannot get any heat out of the heater and don't know if it's because of the vacuum valve and the fact that I have a comp cams 280 in the motor or what the problem is but I would like to have heat, I live in the Northwest. Thanks for any and all help, Timmo

I'll let the guys that are knowledgeable about the heater systems answer your question, but in the meantime, some basic stuff....is there any chance there is a shutoff valve in the heater hose on the engine side? That was a common add-on for lots of the old cars to keep water from circulating thru the heater in the summertime. Mine had one when I got it.
Heater hoses old, new, clogged? Can you tell if there is water circulating thru or at least up to the heater?

working on this problem right now on my 312. In my case I am using a vacuum from the mechanical fuel pump. the butterfly valve under the dash turned out to be defective. If you have a vacuum gauge, hook it to the downstream side of the valve (smaller nipple). When you turn on the heat from the dash control, the gauge should show vacuum. If so, that leads to the valve on the heater core. the test for that is to take a heat sensing gun and measure the temp from both heater hoses. If they are not the same (and close to the radiator coolant temp) the valve on the heater core is bad or the vacuum from the butterfly valve is not getting to the valve on the core. Hope that helps.

If lack of vacuum is a problem Ford also offered a capillary style valve that doesn't use vacuum. I have tried both and prefer the non-vacuum design.

X2, I use a non vacuum also. The less vacuum lines the better. I only have one..

There are plenty of discussions about heaters and heater control valves, but none I saw cover the Ranco style control valve except one from 2010 so I thought this might help someone.  I have the stock heater core with a Ranco valve (no vacuum hose) attached to the core.  Yes, there is a gasket between the two and I can easily see how someone would have issues trying to seal these, but my leak was not located at this seal.  It was on the Ranco valve itself.  As the 2010 post states no one supplies this type of valve anymore so repairing the one I have was the next step.  The Ranco style control valve uses a thermostat to control the water flow depending on the heat setting of the dash control.  The shaft that controls this flow has a rubber seal around it.  This is where mine was leaking.  Fortunately I was able to locate a seal for this from NAPA Balkamp, Part #6601000.  I have included the directions that came with the seal.  I used a rubber O-ring grease on the seal as it was re-installed.  The gasket between the valve and core was in good shape and appeared to be a rubber type material so the same O-ring grease was used.  So far no leaks.

I bought a rebuilt "Ranco" style valve and have not installed it yet. My car had one of these originally but I think it was leaking. I bought the vaccum style, which is two parts, installed it but I did not like it, My cable was almost too short and I had to run a vaccum line which I decided I didn't want. I may be able to find the info on the guy who offers these rebuilt valves if anybody wants one. He pressure tests the valves after the rebuild.

I use that type on mine also. I put in a new heater core and got a used valve from another member here, two years and no leaks so far. I have seen NOS ones on Ebay occasionally. I prefer having the least amount of vacuum lines..

Quote from: lalessi1 on 2015-12-13 08:26
I bought a rebuilt "Ranco" style valve and have not installed it yet. My car had one of these originally but I think it was leaking. I bought the vaccum style, which is two parts, installed it but I did not like it, My cable was almost too short and I had to run a vaccum line which I decided I didn't want. I may be able to find the info on the guy who offers these rebuilt valves if anybody wants one. He pressure tests the valves after the rebuild.

Here is a link to the thread (reply 26) with a picture of the "Ranco" valve and the contact info for the guy I got it from.
http://57fordsforever.com/smf/index.php?topic=5472.15