308 Hudson heat riser fix

metalchipper2
metalchipper2 Member
in The Flathead Forum
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Hello,

I would really like to hear from someone that would answer -correct my understanding of the following.

 On the topic of the Twin H-manifold's heat riser. I understand that with today's gasoline that burns hotter the heat riser should be removed, holes plugged and that enough heat from the engine should keep the carbs from icing up. Also part of the problem is air leaking by the riser shaft introducing oxygen that makes the exhaust burn hotter.

So my question is, after the riser is removed which opens up the passages into the intake.... which to me would allow too much heat up into the intake.

Should I fix a new riser in the open position? And or block off the passage into the intake with a plate of stainless steel? I understand that the surface would need to be reduced.

Also by fixing a new riser, it would be made to smooth the flow out to the collector. Covering up the passages that direct the flow up into the intake. 

I hope the photos help explain my problem.

Thanks,

Metalchipper

Comments

  • ratlee2
    ratlee2 Expert Adviser

    Metalchipper,

    From past conversations, it seems to be a mix between wiring the flapper in the open position and just removing it and installing 2 bolts where the shafts are.

    On my Super Wasp, I run full length Clifford headers with a block off plate that Clifford sold for the underside of the manifold. Here in Michigan, when it drops down in the 40's, I get a thick layer of frost on the carbs until the car is completely warmed up. Once warmed up, the car runs well.


    Rich

  • atc
    atc Member
    https://openforum.hetclub.org/discussion/comment/255778#Comment_255778

    Much like ratlee2, I also run Clifford headers with the block off plate. I mostly drive in Virginia so freezing up is not much of a problem for me. I have had no issues with burning exhaust valves etc. either.

  • metalchipper2
    metalchipper2 Member

    Hello ratlee2 and atc,

    Thanks for your answers.

    I planning on making a new riser, it would be made to smooth the flow out to the collector. Covering up most of the exhaust that passage up into the intake. If that still puts too much heat up to the carbs I will add a block off plate. I am up in good old North Dakota, so have a wide temperature extremes.

    I understand that there is a balance between not enough heat, too cold that causes ice ups and poor vaporization....And too much heat that vapor locks and boils the gasoline up.

    I have been working on replacing the throw out bearing shaft sleeves in the bell housing. the right side was worn out into a C shape.

    Thanks again,

    Metalchipper

  • RL Chilton
    RL Chilton Administrator, Member

    I run a 7X splitter and live in the South. We decided to eliminate and install bolts in holes. I think it does matter when you live in a colder climate.

  • metalchipper2
    metalchipper2 Member

    Thanks RL Chilton

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