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.

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