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Sodium Filled Valves

Discussion in 'The Garage' started by fireplug, Mar 1, 2007.

  1. fireplug

    fireplug 1/2 ton status

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    This is a new one for me. I'm curious what the performance value is as well as the fiscal value.

    There's a motor for sale that seems obviously overpriced to me, and the sellers only real 'defence' is the sodium filled valves. What would you say they were worth?
     
  2. bigblazer87

    bigblazer87 1/2 ton status

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    Mmmm... salty. :D
     
  3. Chevy305

    Chevy305 6 Lug 14bsf Status Premium Member GMOTM Winner

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    Na...

    thats imposible ;) :D
     
  4. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Sodium filled valves are about $25.00 each.

    Sodium filled valves are only found on the exhaust valve and it's purpose is to help keep the valve cool to prevent them from burning when used in an abusive or demanding application.
     
  5. fireplug

    fireplug 1/2 ton status

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    Hehe so I can assume this 'GM crate' with 'only' 33 000 on it was abused?

    The guy is asking slightly more for this motor than a dealership is a warrantied crate 350 and seems determined that his motor is worth it. :confused:

    Next...
     
  6. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    What engine are we talking about anyway? AFAIK GM did not use sodium filled valves in any of the SBC or BBC's ever. Well, maybe the 366 and 427 TD engines but not for light duty cars and trucks.
     
  7. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    I've got a '59 and '63 Triumph motorcycles with sodium filled valves from the factory.....not exactly a modern performance thing. As said, it's to do with cooling properties.
     
  8. xpndbl3

    xpndbl3 1/2 ton status

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    not needed in a truck environment without high repeated rpms such as road racing
     
  9. 1977k5

    1977k5 3/4 ton status Vendor

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    At least some LS1's (maybe even LT1's) have sodium filled exhaust valves.
     
  10. fireplug

    fireplug 1/2 ton status

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    I (obviously) don't know much about them, but since researching a bit I've gleaned, that yes this is old tech, originally for air cooled engines. As an example a lot of aviation info came up in my searches.

    That said, both big and small block motors were associated with them, though I didn't gather whether they were stock that way, with the exception of the Corvette LS7?

    This one in question is a small block 350.
     
  11. ntsqd

    ntsqd 1/2 ton status

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    My grandad's 1962 2 ton Ford had sodium filled exhaust valves in it's 292. They're usually pretty obvious b/c the stem diameter is huge, instead of the normal 11/32" or 3/8" they are ~1/2"+, but note that the stems are usually stepped down to use stock keepers & retainers so you need to look btwn the valve spring coils & not at the tip.
     
  12. diesel4me

    diesel4me 1 ton status Premium Member

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    Sodium-stellite valves..

    I've run into those valves often on air cooled motors, like Wisconsins and VW's,and in industrial engines like Onan's and Continental's....they supposedly don't "burn" as easily as "regular" valves would..

    One word of caution!..DON'T attempt to "grind" these valves on a valve grinder!...I learned the hard way they can EXPLODE if you get them hot enough,and go too far with the grinding,exposing the layer of sodium!..:eek1: --
    We had one blow up while grinding the valves from an International 345 bus motor at the auto parts store's machine shop I worked at!..it scared the crap out of us,and we were lucky none of the shrapnel got us in the eyes...:doah:
     
  13. fireplug

    fireplug 1/2 ton status

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    You want a REAL wake up call through water on it afterwards!

    Note: that is some serious sarcasm, DO NOT do that! :D
     
  14. MaxPF

    MaxPF 1/2 ton status

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    The GM Fast Burn heads have sodium-filled exhaust valves in them. So, any crate motor with the FB heads will have SF exhaust valves.

    Basically, the stem is hollow and is approx. half filled with sodium. At operating temperature the sodium is molten and bobs up and down inside the stem as the valve opens and closes. Since molten sodium conducts heat well it speeds the transfer of hear from the valve head to the stem, where it can be conducted away through the guide and into the cylinder head, thus keeping the exhaust valve head cooler. A cooler valve will last longer, but just as important it helps prevent detonation.This is important in stationary, marine, and truck engines that run under full load for prolonged periods. You can make a longer lasting valve by using better materials such as stellite or Inconel, but it will still run red hot which makes detonation more likely.
     

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