Here is another one of my STUPID questions...

[Kern Dog]

Soon I hope to complete the Classic Auto Air conversion in my 70 Charger. I plan to replace the heater hoses. There are a few "ports" in the big block water pump housing but I don't remember which ones are best for the heater hoses. I have them connected and have so for years....but the heater hasn't worked in the entire time I have owned this car!
With two nipples so close together, it would seem that the heater would sort of just get the coolant in "a loop" instead of a fresh hot supply. Does anyone have a picture or an explanation as to which holes should supply the heater core?
Thanks!

 

[R413]

Looking from front of car.
Top rear outside, closest to block
And lower closest to water pump, behind bracket.

1969 and older both 5/8”
1970 and newer 5/8” low front by bracket, and 1/2” top rear

 

[NoCar2023]

 

[Kern Dog]

Here are a few pictures I found online: The "Top Rear" closest to the block is a 5/8" ? Same with the one furthest forward that "hides" behind the alternator bracket?

 

[Kern Dog]

Maybe I'm remembering something from my Chevy days from years ago but are both hoses the same diameter? I recall my Chevys used a 5/8" and a 3/4".

 

[NoCar2023]

1/2 and 5/8 on big block Mopar. Your going to need these. did mine recently.

 

[NoCar2023]

That is with A/C...maybe none A/C is different.

 

[Kern Dog]

I replaced my RH Iron WP housing with a LH aluminum one last year and installed new nipple/pipes. I just don't recall if I used the correct holes. I have a coolant sensor in another hole, not sure if it is the large one or not.
Jeez...$27 for a couple of those???

 

[NoCar2023]

Damn....how about the heater valve for your car! I saw another one for $400,00
Note the 1/2 hose.

 

[NOSTRT980]

https://www.manciniracing.com/mahehoni19la.html

 

[Kern Dog]

Holeee ****!
The aftermarket heater/Air Conditioning setup is complete. I went aftermarket because I wanted an all electric setup that works great and weighs less. The under dash unit looks to be half the size. Also, the vacuum controls could get wonky if an engine had a rowdy cam.

 

[andyf]

Soon I hope to complete the Classic Auto Air conversion in my 70 Charger. I plan to replace the heater hoses. There are a few "ports" in the big block water pump housing but I don't remember which ones are best for the heater hoses. I have them connected and have so for years....but the heater hasn't worked in the entire time I have owned this car!
With two nipples so close together, it would seem that the heater would sort of just get the coolant in "a loop" instead of a fresh hot supply. Does anyone have a picture or an explanation as to which holes should supply the heater core?
Thanks!

Best way to remember is to keep a spare pump housing on hand to look at. The passages that come out of the top holes in the block carry the hot water. So you want to tap into that for the heater. The water coming out of the heater core is colder so it gets sent back to the water pump. That is why the return line goes to the front fitting. The hoses were the same size on early engines then they got changed to keep people from hooking them up wrong. I'd think your car would have the two different hose sizes. My car is a '65 and back then they used the same hose size for hot side and return side.

 

[Kern Dog]

I changed from the later iron housing with the passenger side radiator hose nipple to a Mancini Racing aluminum housing with the drivers side. The car is out back in the shop but I'll be out there tomorrow to see. The new heater core nipples may be different sizes, they may both be the same. I'll report back on that.
I've only recently been interested in getting the HVAC system working. It will be great to drive it in any weather condition.

 

[Demonic]

In 69, the heater hoses were the same sizes. I believe it was 70 when they went to 1/2" and 5/8".

I would imagine the Mancini pump hose connections would duplicate the factory pump. There will be flow, they're across the impeller.

 

[Big Bad Dad]

I never understood the two different size thing. It is a simple heat exchange coil. The water going in will have to be the same amount as water going out. And I don't see where flow direction would really matter. (Supply VS return.) What am I missing here? Does it really matter? I kind of think it may have just been made to be two different sizes so the production line crew would keep hose routing consistent in the engine compartment....Any other opinions??

 

[BeeKool]

I never understood the two different size thing. It is a simple heat exchange coil. The water going in will have to be the same amount as water going out. And I don't see where flow direction would really matter. (Supply VS return.) What am I missing here? Does it really matter? I kind of think it may have just been made to be two different sizes so the production line crew would keep hose routing consistent in the engine compartment....Any other opinions??

I think it may be a matter of differentiating the two so they dont get confused.
But Im like you and find it to be kind of annoying. My car is going to receive 2 5/8" hoses.

Side note on alot of other vehicles the return line goes straight to the radiator making it easier to discern the lines

 

[bearman]

need to have a restriction on the return side to hold hot water in the heater core. running same size water flow goes in and out to fast. heater will work but takes long to heat up interior. same as fuel should be big going in for supply and little on the return to hold fuel in the fuel bowls and lines. in big rigs they use a restriction fitting or the fuel would just be a loop and cause low fuel pressure. which causes poor power. heater same thing some water must be held in the core to get the heat in the interior. just my two cents

 

[Bad Sport]

need to have a restriction on the return side to hold hot water in the heater core. running same size water flow goes in and out to fast.

That ^^^.

 

[dadsbee]

The reasoning on the flow direction is so no air gets trapped. Coolant in the bottom, out the top.... but the '69's still got hooked up in parallel (reverse to the FSM) on the line with many OE examples of same out there. '70 as noted has two different hose diameters to negate this.

 

[bearman]

that makes good sense and heat rises to make core hot from bottom to top.