Question on Plumbing to Heater Core

[colnago]

All,

I've been buzzing around the 'net, looking for the last few parts I need for my rebuild (I'd rather get new than reuse too much from the old engine). Stupid as it is, one of the items is the fitting from the manifold to the heater hose (and, actually, from the heater hose to the water pump, but I think I can easily get that at AutoZone). In this endeavor, I've found two "pearls of wisdom" that I've never heard before:

1) The inlet to the heater core should be below the coolant level in the intake, so you don't get air trapped in the line going to the heater core, and

2) There should be a restrictor in the line going to the heater core, or you run the risk of too much pressure blowing out the core if you stomp on it.

For #1, I can find fittings that thread into the manifold, and have a tube going below the threads, so it really does only pick up the coolant. For #2, I currently have fittings with valves, so I can restrict the flow by partially closing the valve (although I think it's fully open right now). Of course, right about now, the heater is turned off from the cab, so I shouldn't be getting too much flow/pressure to my core!

So, are either/both concerns for our trucks?

Joseph

[sargentrs]

#1) It already is. The inlet tube and heater core are mounted low on the firewall, below the level of the water pump.

#2) Never had one, didn't come with one, never had a problem.

[Mancar1]

I agree with sargentrs.

[WarEagle]

Joseph may be referring to the control valve in the heater hose line. On my '72, it is manually controlled so you can stop the flow in the summer and increase the flow of the hotter coolant/water in the winter to the heater core for in-cab heat.
I have not heard of pressure high enough the blow out the core, unless it is corroded and about to go anyway. Mine core went out one summer with the heat off so there was no pressure on the core and not much water, but still messy!

[basketcase0302]

like all above said.
And...there is the one valve inline in between the core and the hose from the engine, (that shuts off the supply when your not using it).
The heat from the heater core was always an issue for me in South Florida so I'd put a ball valve in both hoses which helped keep the cab a little cooler, (non AC truck).
If you look at part number #18495 here you can see the valve Joseph:


I also might have the 3/4" heater hose 90 degree ell fitting your talking about if I understand your question right about it needing to go below the threads?

[colnago]

I think I kinda-sorta answered my question, in finding what is actually available. I found a 90-degree fitting, that had an extension down into the coolant fluid. Unfortunately, this wouldn't even thread into my manifold, because of how the manifold was cast (a '73 4BBL "T" manifold that I am putting onto on a '66 352 block). I finally had to order a taller fitting with a shut-off valve, with no extension into the coolant, just so it was tall enough to clear the manifold itself. I ended up spending $20 for what should be a @#%^&* $2 part! I hope it fits; otherwise, I get crazy with my angle grinder.

After sargentrs' reply, I'm not worried about #1, and the fact that this has a shut-off valve takes care of #2.

Joseph

On edit, I wanted either a 45 or 90 on the fitting. I could have bought a vertical non-valve fitting for five bucks, not $20, but I keep going back to only wanting to do this once.