364´Manifold Exhaust Valve

Discussion in ''Da Nailhead' started by Century58, Aug 12, 2019.

  1. Century58

    Century58 Guest

    Because of sometimes hard Starting i checked the Exhaust Valve. What i saw there didn‘t make me happy. The counterweight + shaft i could turn easily, but on the other site the shaft does not move and the Thermostat is lost.
    How could i fix that? Do i need this valve or should i remove it complete?
    https://images.app.goo.gl/ex1oFLeS6c8JH3tD9
     
  2. telriv

    telriv Founders Club Member

    By exhaust valve do you mean the heat riser valve found on the right side exhaust manifold??? IF that's what your talking about the way we drive these older cars today it's not really needed. When they were new they had to operate every day. Rain, shine, ice, etc. The reason was to warm the manifold & carb. in adverse weather conditions to keep ice from building up on the throttle valves & maybe causing the accelerator to stick. I also believe that starting in '57 the intake manifold had holes under the carb. to warm the carb. even quicker in adverse weather conditions. IF the stainless steel plate is not there the exhaust eats up the aluminum carb. base & causes
    all shorts of other problems. Unless of course if you have a Rochester 4GC carb. you won't have that problem as the base is cast iron. I would just remove the valve completely & seal up the holes by plugging or welding.

    Tom T.
     
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  3. Century58

    Century58 Guest

    Thanks, yes thats what i mean. I have the 4 Carb Rochester. So i will remove it, because i think its closed all the time ;-)
     
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  4. Century58

    Century58 Guest

    Here still my feedback. After everything was removed, I had to notice that someone had already removed the valve.
    Nevertheless it was no mistake, because the manifold gasket and the carburetor preheating were defective.
     
  5. John Codman

    John Codman Platinum Level Contributor

    My 425 has no heat riser valve but the carburetor still got enough heat the on a hot day it would vapor lock. I drilled and threaded the exhaust passage holes under the carburetor (an Edelbrock 4bbl) and installed bushings in them that reduce the holes' diameter from about 1/2" to 1/4". The engine runs great and no more vapor lock. In fairness, I did two modifications at the same time; the other was to install the Air Conditioning fuel filter with a return to the tank. Whether it was one mod or the other, or possibly both together that solved the vapor lock issue, I now trust the 425 (431 actually) to start hot.
     

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