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I have posted a question in the past regarding the attached photo of a shaft that runs through the manifold on a 38 6 cylinder engine. One end has a slot that protrudes out of the manifold. There is an obvious exhaust leak there. It appears that their was a piece attached at one time. Can someone explain to me if there is a way to seal this to stop the exhaust leak. Thank you

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Looks like part of the heat riser valve. Here is a photo from a later manifold but the setup was typical for many years. The slot would be for the thermostatic spring and the other end had a weight.

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I had a similar problem on my '39 6cyl, the shaft and plate were frozen in the closed position and the motor wouldn't run well as it warmed up. I pulled it all out while I had the manifold off, taped the holes for some 3/8 pipe plugs and screwed them in. I cut a piece of 1/16th copper plate to seal off the bottom of the intake side and all is working well.

Hi John,
When I removed the shaft I did not feel resistance as if something was connected to the shaft. I wonder if it would be ok to tap and plug both sides of the manifold ? What do you think ?

Thank you HH 56 for the diagram

If your motor is running OK now but just has the exhaust leak then it would certainly be worth a try to tap and plug the holes. You could easily fix this later on if you have the manifold off the car by making some press in bushings.

Thank you John , the engine runs great, I think I will do just as you said.

We run into issue fairly often at our restoration shop as many other engines besides Packard used a similar design. We normally remove the shaft, flap, and spring. Then enlarge the holes install bushings and then fitting the bushings to the shaft. In some cases we will make a new shaft as they can have grooves worn into them from years of use. We then reassemble and lubricate with graphite. Think of it like a throttle shaft on a Carb. A good machinist should be able to do it for you if needed.

Thanks
James