Alright WHO can explain this one!

[oldrelics]

This is an original exhaust crossover pipe from a '40 truck. I just happened to look inside and surprize! what the heck is that?

[maud]

Looks like your truck has been "Fixed"?

[oldrelics]

It appears to be some sort of insert slid in to the tube. The piece inside is V-shaped. A baffle? but why?

[alcan]

Could be a " duck bill" style heat riser valve. I've heard of them but never seen one.

[Barlea]

That's the early form of heat riser valve called a duckbill, later changed to the bimetal coil with counterweight. ..B.

[Kurt in NJ]

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Looks like someone wanted all the exhaust from that bank to go through the crossover in the manifold --the only reason I can think of is to burn fuel that needs to be heated ---was there anything else different? ---a heated fuel line?? ,I have read about conversions to burn kerosene, or diesel, the diesel requires the hot manifold and hot fuel --perhaps it was part of a wartime conversion that was forgotten, how did it run??

[Ol' Ron]

This was review in JWL's book. He discovered it after he ran some teses. After removing it there was no improvememt in power.

[rotorwrench]

A person might apply some heat to it with a heat gun or a propane torch and make sure it still opens up. If they get cracked, they might not open up sufficiently.

[Old Redneck]

Some pipes had a inter wall pipe . I seen a plymouth that would not run and when I disconnect the header pipe the car ran ok. Look inside the pipe and that was the problem. Its happen's.