350 heat riser questions

Discussion in 'Small Block Tech' started by MrSony, Nov 27, 2018.

  1. MrSony

    MrSony Well-Known Member

    1. Am I supposed to be able to move the flapper by hand? I cannot, it seems seized.
    2. What direction does the little lever spring go? Does it go in the slot in the shaft or rest against it as shown?
    3. Do I use a gasket, sealer or just metal to metal when installing?

    any input as always is appreciated.
    riser1.jpg riser2.jpg riser3.jpg
  2. gstewart

    gstewart Well-Known Member

    Never saw one like that. Only remember those wit a counterweight.
    The outer spring, in the picture in that position,is probably there to slow down the butterfly opening and closing and maintain position.
  3. mrolds69

    mrolds69 Still restoring!!!

    From memory only, that looks about right. The flap in the valve should move easily. Typically the valve is shut, the flat, wound spring holds it closed. If it were a new valve, it would be closed, then you could move it to the open position against the spring tension. Then if you let go...it would shut because of the spring. Try penetrating oil on the shaft where it goes through the main piece. See if you can free it up. You have to get that flap moving freely. You could just cut it out, but they do serve a purpose. I forget, but I thing there is nothing between the valve and the manifold. No gasket, but GM did use some kind of sealer there...and on the pipes where they were clamped at the factory. There is another option, if you are the kind of guy who likes to toss starter brackets, heat shields and stuff like that! Once it's working, it will work fine.
  4. Schurkey

    Schurkey Silver Level contributor

    Bottom side: has cast-in "donut" that seals to the downpipe.
    Top side: probably needs a flat gasket, obviously high-temperature.

    Flat-wound spring: bimetal, controls the opening of the heat riser valve.

    Hairpin spring: anti-rattle, no real function other than it prevents the valve from making noise.

    The valve should open and close easily. They often seize. GM and Chrysler (Probably Ford and AMC also) each sold a "special" penetrating lube for heat risers. The stuff had a distinctive odor. Closest I can get to that spray now is A/C Delco aerosol 10-4020. Smells about right, but it's Low-VOC and so "green" you could probably drink the stuff.


    Why are you starting two threads on the same heat riser?
    Last edited: Dec 15, 2018
  5. Schurkey

    Schurkey Silver Level contributor

  6. MrSony

    MrSony Well-Known Member

    Forgot I made the other thread, to be honest. Didn't remember it until you linked to it. Thanks for the info Schurkey.

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