Can someone explain this port please

[Boduke]

That hole there is where you store miscellaneous screw, clips, linkage parts etc. I usually keep my only accelerator pump clips in there.

Cubby hole

 

[Lonewolf3165]

That’s where your money gets sucked into. Blocking it off does no good. It has mystical powers.

 

[Professor Fate]

Really, @wasteddays ? A red X? What can you possibly disagree with?

 

[Donny DartO]

This is how it looks right here. Those remaining open crossover ports let the heat out.

View attachment 1716090841

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So now I understand the crossover port, but is it ok to block it off? And will a gasket just like in this picture do the job?

 

[cudamark]

The crossover allows exhaust to pass through to the other side when the heat riser is closed. It also heats the choke spring and keeps the carb from icing up under certain conditions. If you don't need those features, sure, block it off. A metal intake gasket will do the job.

 

[George Jets]

So now I understand the crossover port, but is it ok to block it off? And will a gasket just like in this picture do the job?

And yes, remove the heat riser in the passenger exhaust manifold. We take the butterfly and shaft out, then weld the 2 steel sleeves shut to block the holes.

Now the exhaust will free flow out through the exhaust system, and there will be no hot gasses trying to push across the intake manifold ports with the block off gaskets installed.


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[Dartfreak75]

I've took apart several engines that have a little piece of metal rtved over the hole then the gasket over it. I personally do not block it off on a engine built for the street. A race engine is a different story. But if I was building a race engine I wouldn't be using factory cast heads.

 

[Donny DartO]

And yes, remove the heat riser in the passenger exhaust manifold. We take the butterfly and shaft out, then weld the 2 steel sleeves shut to block the holes.

Now the exhaust will free flow out through the exhaust system, and there will be no hot gasses trying to push across the intake manifold ports with the block off gaskets installed.


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I have headers for it anyways. When you say weld the two sleeves, you must mean the ports on the heads, I tried to have a welder do that for me and he gave me a long explanation about the difficulty of welding cast iron. But I do have a MIG and I've seen some YouTube videos where they show it's been welded, should I just booger it up or is high risk for cracking?

 

[George Jets]

I have headers for it anyways. When you say weld the two sleeves, you must mean the ports on the heads, I tried to have a welder do that for me and he gave me a long explanation about the difficulty of welding cast iron. But I do have a MIG and I've seen some YouTube videos where they show it's been welded, should I just booger it up or is high risk for cracking?

No welding on the cast iron heads.

It is the factory cast iron exhaust manifolds that have the steel pivot sleeves in them, that can easily be welded shut with a wirefeed.

If you are using headers, problem solved > no heat riser.


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[Boduke]

And yes, remove the heat riser in the passenger exhaust manifold. We take the butterfly and shaft out, then weld the 2 steel sleeves shut to block the holes.

Now the exhaust will free flow out through the exhaust system, and there will be no hot gasses trying to push across the intake manifold ports with the block off gaskets installed.


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Dont forget the mystery holes in the front. I chased that leak for a weekp

 

[65 Cuda 340]

And yes, remove the heat riser in the passenger exhaust manifold. We take the butterfly and shaft out, then weld the 2 steel sleeves shut to block the holes.

Now the exhaust will free flow out through the exhaust system, and there will be no hot gasses trying to push across the intake manifold ports with the block off gaskets installed.


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I timed my 56 Plymouth with a GTech not long after I got it. 277 poly, four barrel carb, dual exhaust, Powerflite trans and 200 gross horsepower. Ran 18.60. Now I didn't expect it to be fast, but I thought it shouldn't be THAT slow. So, pulled the right side exhaust pipe from the exhaust manifold and, sure enough, the heat riser valve was stuck completely shut. Took it out with some vice grips and a little cussing, left the shaft in. Now it ran 17.80.

Friend said, wow, that's a huge difference. I was kinda surprised it didn't make more difference than that, since with the closed valve, virtually all the right side exhaust (except what little sneaked by the closed valve) was forced into that one little heat riser passage and out the other side into the driver's side manifold. Probably would have made more difference with a more powerful motor.