1956 exhaust control valve purpose? | Ford Thunderbird club group 1955-2005 T-Bird models

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1956 exhaust control valve purpose?

  • Thread starter Thread starter Shawnski
  • Start date Start date
Shawnski

Shawnski

Gold Member
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Thunderbird Year
1956
What exactly is the purpose of this valve? Is it just there for a faster warm up?
It appears to remain closed during idle even after it’s warmed up, and it opens as the accelerator is pushed. I would expect this to stay open all the way once the engine has reached operating temperature.
Mine moves freely, I’m just confused as to why it doesn’t stay open…🤷‍♂️

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There should be a bimetallic spring on it. When the car is cold the valve is closed which forces exhaust gas to go thru the crossover under the carburetor. As the car warms up the bimetallic spring opens the valve and greatly reduces the amount of crossover exhaust gas. If the spring is missing and the valve is moving freely the force of the exhaust will push it open when the engine is at higher rpms. You can completely remove the valve or you can wire it open. Unless you live in the frozen north and drive in the winter you don't really need it.
 
I’m in Southern California, so we seldom see temps under 50F and we wouldn’t take the her out anyways in that temp..
It does have the biometric spring, but it seems really loose. According to the manual, even after the car is warmed up, the valve will close partially while idling. Makes no since to me and honestly that’s typically when the coolant temps rise.. no need for excessive heat during idle.
I’m going to temporarily wire it open and go for a drive to see the effect on coolant temperature.. Thanks for the reply!
 
Shawnski said:
I’m in Southern California, so we seldom see temps under 50F and we wouldn’t take the her out anyways in that temp..
It does have the biometric spring, but it seems really loose. According to the manual, even after the car is warmed up, the valve will close partially while idling. Makes no since to me and honestly that’s typically when the coolant temps rise.. no need for excessive heat during idle.
I’m going to temporarily wire it open and go for a drive to see the effect on coolant temperature.. Thanks for the reply!
Click to expand...
Most of the classic bird vendor sell a replacement for this in three forms: (1) a direct operative replacement; (2) a spacer that looks like the original but has no flapper; and (3) a simple spacer with no original looking hardware.
 
83ragtop50 said:
Most of the classic bird vendor sell a replacement for this in three forms: (1) a direct operative replacement; (2) a spacer that looks like the original but has no flapper; and (3) a simple spacer with no original looking hardware.
Click to expand...
I don’t know whether it has to do with the volatility of modern (premium) gas, but I run the spacer plus the truck-style intake gasket in the dead of midwest winter with no warmup problems. If your choke is properly adjusted, removing or tying open the valve shouldn’t be an issue.
 
Thanks for your views and thoughts. Our winters are pretty much nonexistent. I do have the choke set up and it works well. Like I had mentioned, I’m going to tie it open and see how she performs. I don’t expect any issues. I’m actual more hoping that in local stop and go traffic, she runs a little cooler.
 
The function of this valve was to keep the warm exhaust air in the manifolds for a longer period of time when the engine is cold. This would warm the manifolds faster, which would warm the choke faster. Since this valve is not needed if you do not drive the car in cold weather, I removed the bimetallic spring and turned it around, so it holds the valve open when cold. Since the valve is installed with the weight pointing downward, when the spring warms then the weight takes over and holds the valve open.

doug7740
1955 Thunderbird Blue

Heat Riser.jpg
 
Once the car is up to operating temperature, the valve should stay completely open. If not, someone may have would the spring to tight. These tend to stick in the open position as they should spend their life open every time the engine warms to normal operating temperature. I agree with the above, in Southern California, I just put the pacer in. If your valve is not leaking from the shaft, you can alco remove the plate on the inside and then it looks like it is there and you have no restriction.
 
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