1970 vs 1974 heater valve

[CBODY67]

Cripes!!!, I never thought of that, so thank you, but now I'm really confused.

All pre 1973 pictures of 440's I've seen have 4 port or no heater valve.
After 1973, some 440's have 2 port, some have 4 port.
All mopar engines pictures I've seen except 440 have 2 port.

Why did engineers add expense of a 4 port than a simple 2 port? Maybe they found added pressure on the water pump when using a 2 port since it cuts off flow or adds backpressure? Or coolant is starved to the engine? Maybe they changed this defect after 1972 on all 440's? I don't know.

(To change to cable, I'd have to rip the dash apart. Too much work) I really appreciate all your help. I guess I'll play around and let you know in the summer.

Even Dyno testing, they don't just simply cap it off. I don't know.
View attachment 572222

Unless you can find some "side channel" to connect the two tubes, the ONLY tube which is throttled is the supply side to the heater core. Whether Chrysler, Ford, or GM. The return line should be completely open for unrestricted flow back to the cooling system.

Why the 4-port (actually 2-port, just counting each side)? Probably had to do with the assy line operation of hooking up the heater hoses on the Fuselage cars, I suspect. The Slabs had everything out in the open, for the heater core connections. The Fuselage cars had them more hidden (ala GM-style), so it was easier to put the heater valve on the fender apron with the heater core hoses hooked to it as the engine was dropped into place. Then, the engine (with heater hoses attached) was installed and everything hooked up. Coolant didn't get installed until later. That is my suspicion . . . no real engineering reason, just the dynamics of putting things together on the assy line.

Another consideration is that with the heater water valve bolted to the apron, both the normal valve and the ATC valve would be mounted in about the same place, which would make for a more uniform situation on the assy line, no matter the HVAC system.

I highly recommend an assy plant tour, no matter the brand, as it can answer lots of questions about how all of the parts come together to make the final product. Do one for unibody cars and one for body/frame pickup trucks. The differences in how things are sequences are very significant.

Happy Holidays!
CBODY67

 

[Northcoast300h]

Just FYI for others with this problem - I installed the 1974 heater valve pictured above. Yep, it works backwards. Vacuum closes the 1974 valve to the heater core instead of opening it as on the 1970 heater valve. It seems most or all heater valves work this way. Big_John's idea is a good one, however I'd like to get my A/C and heat to work the way Chrysler intended. So looks like I'll pay the $100 for the 1970 heater valve and hope again that it doesn't leak.

 

[Northcoast300h]

The original Chrysler bakelite/phenolic heater valves were junk. The would last maybe 2 years at best before they cracked and started leaking. I have a bunch of them but I won't use them because one never knows when they will crack and start leaking until one notices the engine temperatures start climbing due to leaking coolant. But in the case of the early 70s Chryslers, they only had hot lamps to let you know your engine just got fried because of one of those pieces of junk started leaking while driving down the road. I like to keep my cars usually as much nos stuff as possible, but that won't happen with those crap valves.

The aftermarket has supplied non-original metal heater valves for a very long time and I have yet to need to replace one. They do not, however, modulate the temperature as smoothly as the original ones did.

I have to wonder how many customers never bought another Chrysler product after being stranded on the side of the road a couple times with the original valves. Yeah, they saved a lot of money for the Corporation but they lost so many customers as a result. That's OK though, because the manager of the department got promoted due to his ability to cut costs and went on to his next assignment to continue to lead the company into bankruptcy by 1980.

How are you able to run Imperial mufflers - those were really long and with a large circumference as well and worked well to quell exhaust noise? I haven't been able to find any mufflers in the aftermarket for decades that were as long and effective in muting sound like those did especially when used in conjunction with resonators positioned near the end of the exhaust pipe(s). Like you, I want my cars quiet and do not like to hear the drone of the exhaust hour after hour of driving.

What aftermarket non original metal heater valve are you using? I've searched everywhere and can't find one. Thanks

 

[saforwardlook]

What aftermarket non original metal heater valve are you using? I've searched everywhere and can't find one. Thanks

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