exhaust control valve

[billfish]

The green book says my 51 ford has a "duck bill" type exhaust control valve. This valve is located in the exhaust crossover pipe. Are there symptoms that would warn you that this valve is not operating properly? I would be surprised if this pipe was ever disassembled or if this valve was ever inspected.

 

[paleot]

I started mine with a stuck valve, I call it a heat riser valve. The heat riser passage under the carb soon turned black and the carb was near boiling over from the heat. I took it out and put shorter studs to bolt the crossover on. I don't need the heat riser in s/w Louisiana.

 

[Bruce Lancaster]

There were two types used, not sure what years...
I think Paleot is referring to the conventional type with a throttle type butterfly inside and a thermostat coil visible on the outside to move it.
The "Duckbill" was entirely inside the pipe and not visible without disassembly. It was a strange warped piece of (I assume) bimetal shaped like a Chinese fortune cookie...or a duckbill. It pretty well blocked the pipe when cold and warped into a more compact shape to allow flow when hot.

 

[billfish]

Is there any way to determine if this valve is working without taking the pipe apart?

 

[paleot]

You are right Bruce, mine had the external spring and round cast iron weight.

 

[Bruce Lancaster]

I think only way to tell is full of guesswork...see how fast each manifold gets hot, and I would also expect as Paleot says to have carburetor get real hot.
I have the simple valve type on my '48, and long ago I pulled it to check things out. The actual butterfly plate had completely corroded away, leaving only the shaft across the pipe!