OE Exhaust Valves, Sodium Options

[914werke]

I know Jake suggests tossing these, but unfortunantly Im rebuilding a set of heads. Id like to keep them stock, but Im more concerned about longevity.
Is there anything that can be done to improve thier function?

Cryo? (IMG:http://www.914world.com/bbs2/html/emoticons/sad.gif)

[r_towle]

Im gonna ask a rhetorical question...

Did the original valves last 100k miles?

Will you drive this car more than another 100K miles???

Rich

[914werke]

Actually yes! and that IS the hope. (IMG:http://www.914world.com/bbs2/html/emoticons/smile.gif)

[Bleyseng]

toss em as they are 30 years old! Buy new ones if you are dying to have sodium exhaust valves.

I would just install SS (IMG:http://www.914world.com/bbs2/html/emoticons/popcorn[1].gif)

[alpha434]

QUOTE (Bleyseng @ Apr 1 2006, 10:51 PM)

toss em as they are 30 years old! Buy new ones if you are dying to have sodium exhaust valves. I would just install SS (IMG:http://www.914world.com/bbs2/html/emoticons/popcorn[1].gif)

SS as in Stainless Steel?

Stainless steel conducts heat faster than steel. And the reason sodium filled valves were used was to STOP heat conductivity. Titanium doesn't conduct heat as fast as steel either. But stainless would be a huge downgrade.

Chances are that the ones you have are good. Clean 'em up. Reuse 'em. No problems. Just remember to keep the same valves matched to the same ports on the heads, or to polish them if you're using new heads.

[Brando]

QUOTE (alpha434 @ Apr 1 2006, 09:56 PM)

QUOTE (Bleyseng @ Apr 1 2006, 10:51 PM) toss em as they are 30 years old! Buy new ones if you are dying to have sodium exhaust valves. I would  just install SS (IMG:http://www.914world.com/bbs2/html/emoticons/popcorn[1].gif) SS as in Stainless Steel? Stainless steel conducts heat faster than steel. And the reason sodium filled valves were used was to STOP heat conductivity. Titanium doesn't conduct heat as fast as steel either. But stainless would be a huge downgrade. Chances are that the ones you have are good. Clean 'em up. Reuse 'em. No problems. Just remember to keep the same valves matched to the same ports on the heads, or to polish them if you're using new heads.

But how quickly does stainles steel dissipate heat to the valve seat, compared to sodium-filled exhaust valves?

From what I've read, Stainless is NOT a good head conductor, and dissipates heat quite rapidly to surrounding conductors. Currently reading up on it's thermal-dynamics.

[messix]

the valve stems are filled with sodium to isolate the heat to the head of the valve.
you want high heat transfer to the valve seat to keep the valve cool.

[DNHunt]

QUOTE

Is there anything that can be done to improve thier function?

I can think of 1 thing that helps indirectly at least. Keep the heads cool. Don't lug it. Keep the fins clear and the cooling system in good shape. Keep it timed right. Yada, yada, yada

After following you a couple times forget the lugging comment cause you never go slow enough to lug it.

Aren't I a lot of help.

Dave

[davep]

QUOTE (alpha434 @ Apr 1 2006, 09:56 PM)

And the reason sodium filled valves were used was to STOP heat conductivity.

Absolute nonsense. The liquified sodium in the valve stem sloshes back and forth to transfer heat faster from the valve head to the stem. Then through the valve guide and into the head. This design is like a heat pipe that is so much in vogue in heat transfer circles today, but does not use two phase operation and instead requires mechanical motion.

Now titanium is a good insulator, and tends to trap the heat in the valve head, comparatively speaking. So this lightness of the Ti valve is offset by its heat transfer characteristics.

[Bleyseng]

I don't use 30yr old valves in my cars....if you want go ahead. SS valves are much improved over 30 yr ago too and 30yr old valves like to lose their heads. (IMG:http://www.914world.com/bbs2/html/emoticons/dry.gif)

[J P Stein]

QUOTE (davep @ Apr 2 2006, 04:59 AM)

Absolute nonsense. The liquified sodium in the valve stem sloshes back and forth to transfer heat faster from the valve head to the stem. Then through the valve guide and into the head. This design is like a heat pipe that is so much in vogue in heat transfer circles today, but does not use two phase operation and instead requires mechanical motion.

This is the internet, Dave......where nonsense passes for fact....you got a problem with that? (IMG:http://www.914world.com/bbs2/html/emoticons/laugh.gif)

[r_towle]

Here is my logic.

The car/engine was designed for longevity, not super performance...

It was designed by alot of engineers...real automotive engineer, with dynos, testing equipment etc...

the original valves last 30 years, provide 100k+ of service.
They work with the stock motor design.

If I am rebuilding a head, stock motor, stock vavle sizes...I use stock valves, sodium filled.

I would never re-use valves, not worth it.
The top of the valve stem is usually mushroomed, and needs to be re-ground, and re-hardened. not an easy DIY process.

The new valves are 55 bucks ...

I would say, dont re-use, but go with what the orinigal engineers specified for this motor...the same conditions...you will get another 100k plus from the motor.

The original seat material has been upgraded, that was a failure point..so get the seats replaced.

The valve guides are normally beyond service at 100k miles, so you will need to replace those as well.



Rich

[ConeDodger]

...and for a fun experiment you can do at home! Cut open the old liquid sodium filled valves and pour that liquid sodium down the sink! Your kids will love it! Your wife... Well, not so much. She will be needing that new kitchen now, thank you!

Actually, I agree. The head rebuilders who do mass quanitity not quality are going to toss them and use new valves that are not sodium filled. They might give you the same arguement about 30 YO technology but what it really boils down to is that $55 per valve. Performance head rebuilders might use something different because they are working with different set of goals. If you don't want to rebuild those heads every few years you probably want to use sodium filled valves...

[r_towle]

what happens when you pour it down the sink??
smoke?
Fire?

come on...do tell..anything cool??

Rich

[bd1308]

QUOTE (r_towle @ Apr 2 2006, 10:57 AM)

what happens when you pour it down the sink?? smoke? Fire? come on...do tell..anything cool?? Rich

My dad had access to his chemistry teacher's closet of stuff. He grabbed a sample of sodium (fist sized) and took it to a local lake....him and a buddy threw it in a lake and it floated down a little bit and he watched in horror as it floated nearby a bridge, and just before it got to the bridge BOOM! and a large column of water surged up from the lake!

if you put potassium (small amount 1/4 dime size) in a coffee pot with water..it'll blow the coffee pot apart.

b

[J P Stein]

QUOTE (r_towle @ Apr 2 2006, 08:57 AM)

what happens when you pour it down the sink?? smoke? Fire? come on...do tell..anything cool?? Rich

You don't even have to get it wet.....the humidity in the air will set it alight. Nuthin' to fool with.....

[ConeDodger]

QUOTE (r_towle @ Apr 2 2006, 08:57 AM)

what happens when you pour it down the sink?? smoke? Fire? come on...do tell..anything cool?? Rich

Oh sorry Rich, Liquid sodium explodes when it contacts water.


Liquid sodium + Water = Boom!

[Jake Raby]

I can't stand not posting on this topic.

If Stainless valves are horrible I have over 900 engines that are time bombs! Thats because I have not used a Sodium filed valve since around 1994 for ANY APPLICATION!

The Sodium valves were leading edge in the 1970s, today the technology behind the tainless valves is much higher than it was in the 70s. I have had 3 valve failures with stainless valves in the past 7 years, two of which were in full blown race engines, spinning 8,000 RPM and the owner did not complete valve adjustments at my specified intervals. The last one was recent when a customer installed a set of ratio rockers against my recommendations without even checking valve train geometry. It was an intake valve, not an exhaust!

All my personal cars run stainless valves from SI industries along with all my engines. This includes engines in my "Super Hero" line up, even the Mighty Spyder! Not all stainless valves are created equal, some are pure junk, while the SI valve is incredibly strong and light and can take the abuse of a full bown race engine.

For someone to recommend a used sodium filled valve over a brand new Stainless version is pure stupidity and shows one thing: lack of experience! I had to read that one 3 times and I still didn't believe it- pure bullshit!

Thats because experience teaches us at teardown what fails and if you had seen as many engines blown to bits BECAUSE OF SODIUM VALVES as we have you certainly would not make this statement. Have one failure due to Sodiums and you won't say it, see a few dozen more and you'll be about as experiebced with it as we are.

When a Sodium valve goes without adjustement, or when it gets ready to let go the valve explodes and blows the piston and even the cylinder to bits! I have had this happen on my 914 engines when it was stock and nothing could be reused- not even the case, or the crank or even the rods! I have seen this many times and even more severe. I posted the pics of the failure in 2002 and most people swore the engine was turning 8K, nope a chick was driving it!

The other issue with Sodium valves is that they are only made in 9mm stemmed versions that weigh about 17 grams more than our stainless steel version and 17 grams of valve mass is worth it's weight in gold for valve control.

So there ya have it, the view that experience has taught me about Sodium valves. We do not use Stainless valves because they are cheaper, we use them because they are BETTER- period. Racer Chris turns his 8,500 RPM for a full season with no sweat at all in a 186HP 1832cc engine, that should speak volumes.

Okay, back behind the curtain, I just had to stop the Bullshit that was starting to get deep in this thread!

BTW- if you don't agree with me, then (IMG:http://www.914world.com/bbs2/html/emoticons/pissoff.gif)

(IMG:http://www.914world.com/bbs2/html/emoticons/ohmy.gif)

Hey, maybe someone should go chuck up a Sodium valve in a valve grinder and see what happens. Alpha, wanna go try it?? You'll be geting out of the hospital about the time I come back to the forums, I would hate for you to miss my posts-

[Aaron Cox]

(IMG:http://www.914world.com/bbs2/html/emoticons/owned.gif)

[r_towle]

QUOTE (rdauenhauer @ Apr 1 2006, 11:04 PM)

I know Jake suggests tossing these, but unfortunantly Im rebuilding a set of heads. Id like to keep them stock, but Im more concerned about longevity. Is there anything that can be done to improve thier function? Cryo? (IMG:http://www.914world.com/bbs2/html/emoticons/sad.gif)

I believe STOCK is the operative word here.

Again,,,designed to provide longevity..not turn at 8500 rpms...

As far as owned goes...well whatever...I personally like the free flow of information that people have on these types of forums...I think everyone here has lost some balls...no one speaks up anymore for fear of getting bullied...

I dont like bullies,

Rich