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-   -   Sodium filled valves (http://www.clubcobra.com/forums/fe-talk/75336-sodium-filled-valves.html)

xracerbob 12-21-2006 08:25 AM
Sodium filled valves
 
Many years ago I had a 427MR that dropped an exhaust valve and broke a piston. Apparently the guy who did the heads used sodium filled valves and not the Manley valves I had specified. I never hear any talk about these valves and am assuming nobody uses them so they don't go through the nasty experience I had.

Anybody using these? They were supposed to be lighter I believe.

SJK2 12-21-2006 08:49 AM
I think they are used on new vettes...

http://www.corvettemuseum.com/specs/2006/LS7.shtml

Excaliber 12-21-2006 09:18 AM
Seems to me sodium filled valves used to be fairly common 'back in the day' and widely available for lot's of different motors. You don't hear much about them today except for things like 'they break'. I don't know if thats really the case or the valves are just getting a bum rap.

Steve, I checked that link, sure enough it says sodium filled exhaust valves on the new Vette.

Rick Parker 12-21-2006 09:36 AM
The sodium valves were OEM in the side oiler and were the achillies heel in the valve train. I think the manufacturing processes at the time led to the potential of having the stem fracture at the underside of the valve. The theory is that the sodium helps disipate some of the heat in the valve. Metallurgy marched forward and different alloys of Stainless were used for the valves as was Titanium in some types of racing but the wear on the seat and valve face limits Titaniums usage.

Yetiman 12-21-2006 09:42 AM
VW has been using them on several of their supercharged and turbo motors since the early 90's, and they have been nothing but reliable in those engines.

Igofastr 12-21-2006 10:17 AM
I use them on the exhaust side of my Porsche 912 motors. In fact, just about everyone does. No problems with breakage, and better cooling than stock.

olddog 12-21-2006 10:34 AM
I read that Ford did use sodium filled valves on the 427 back in the day (think only on the exhaust). They reportedly did it to be able to run higher RPM via the lighter valves (other benifits may apply). Heads breaking off of these valves were very common. Drag racers of the day had different opinions. Some quit using them others replaced then after a few runs.

Better material and manufacturing practises may exist today. Maybe the old problems have been solved. However these are relatively large diameter valves, mind you. Just because a Porsche can run them without issues, does not necessarily mean they will work on a relatively monster sized valve in a big block.

Unless you are building a high rpm FE, they likely are not needed. Sounds like a risky path to me.

Woodz428 12-21-2006 11:21 AM
They were used for many years on VW van engines, I still have several new ones left over. My understanding regarding the 427 valves was that they would pop the head if they weren't warmed up to temp prior to hammering them. The sodium turns to liquid under heat and the sloshing aided in cooling of the head. I never used them because of the extra expense and the spotty record. The ones in the VWs never encountered a problem like that, although VW valves in general will pop heads after extended use in an engine from stem heat fatigue crystalizing the grain structure. I think the lightweight, head diameter in relation to the stem, plus lower revs made them less of a problem than the 427s were.

avanti-176 12-21-2006 01:41 PM
I have gmpp aluminum "fast Burn" heads on my 390 stroker sbc, this passage is taken gmpp's site........

Quote:
D shaped 78cc exhaust port and runners provide exceptional flow for applications well in excess of 500 horsepower.
Raised runner (.240 higher than conventional 23° head) intake ports with 210cc ports and runners provide exceptional flow for applications well in excess of 500 horsepower. Raising the top of the intake ports provides a better “line-of-sight” through the port and onto the back side of the intake valves.
The 62cc fast burn combustion chambers are the most efficient combustion chambers ever to be incorporated on a GM Performance Parts cylinder head. Their Fast Burn efficiency produces higher cylinder pressures by burning more of the available fuel before the piston starts its power stroke downward. Additionally, by more completely using the available fuel, the head ensures that an engine is producing more power for a given quantity of fuel.
The Fast Burn head’s specially designed valve seats will accommodate up to 2.02 intake valves and 1.600 exhaust valves. Their design also provides superior structural characteristics.
The 2.00 hollow stem lightweight intake valves are utilized to provide exceptional flow and intake charge velocity. Their light weight makes them suitable for sustained high RPM applications as well as reducing loads on valve springs, rocker arms, push rods, roller lifters and camshaft.
The 1.56” sodium filled lightweight exhaust valves have all the same great benefits of the hollow stem intake valves. In addition, they are able to perform in extremely high-temperature performance applications.
Interesting that they only use the sodium filled stems on the exhaust. I have not broken one yet, and they really rev.

Dan

edwhite7 12-26-2006 05:46 PM
It was my understanding that there was only a problem when using high lift cams, over .600 lift, because of the hard return. They are much lighter.

Woodz428 12-26-2006 07:13 PM
Quote:
Originally Posted by avanti-176
I have gmpp aluminum "fast Burn" heads on my 390 stroker sbc, this passage is taken gmpp's site........



Interesting that they only use the sodium filled stems on the exhaust. I have not broken one yet, and they really rev.

Dan
I think the exhaust are usually all that get the sodium treatment, since they only flow hot gases they benefit most. I think that the 427 ones were just the exhausts, although I'm not positive. They were used on the FT exhausts and the exhaust was the only valve that VW used them on. The FT and the VW also had bigger diameter valve stems, which would reduce flow, but the 427 ones had standard stem diameter. That may have also lead to some of the failures. I don't recall seeing either the VW or the FT valves ever "popping" as would happen with the 427 ones.

Bob In Ct 12-26-2006 08:31 PM
No need to use them on intake valves since they are against the head when the fire is burning. When they open a cool intake charge comes by. The exhaust valve, on the other hand, gets a very hot flame all around it 25 times per second at 3,000 RPM. The longer the duration the less time it has to cool against its seat. It's a tough life being an exhaust valve.

Bob

SFfiredog 12-28-2006 12:38 AM
There is nothing wrong with NEW sodium filled valves...
 
Sodium filled exhaust valves are used in nearly every air-cooled engine, especially air-cooled aircraft engines.
The main design use is to dissapate heat, not really for light weight.
That's why they are so important in air-cooled engines.
The problem with sodium filled valves is the sodium creates corrosion inside the valve stem.
Sodium (salt) corrodes metal. The older the valve, the more the corrosion, new or used.
It was common practice to replace the exhaust valves after every race on the Ford NASCAR teams 427s and Boss 429s.
Forty + year old OEM Ford valves, wether they are used or NOS, are ticking time bombs in your engine.
We used to X-ray the sodium filled valve stems to be sure they were ok to use. I found so many that were paper thin that I decided never to trust old valves, NOS or not.
I stick with stainless steel on the street and titanium on the track.
HTH,
--Mike

Naumoff 12-28-2006 05:10 AM
Quote:
Originally Posted by SFfiredog
Sodium filled exhaust valves are used in nearly every air-cooled engine, especially air-cooled aircraft engines.
The main design use is to dissapate heat, not really for light weight.
That's why they are so important in air-cooled engines.
The problem with sodium filled valves is the sodium creates corrosion inside the valve stem.
Sodium (salt) corrodes metal. The older the valve, the more the corrosion, new or used.
It was common practice to replace the exhaust valves after every race on the Ford NASCAR teams 427s and Boss 429s.
Forty + year old OEM Ford valves, wether they are used or NOS, are ticking time bombs in your engine.
We used to X-ray the sodium filled valve stems to be sure they were ok to use. I found so many that were paper thin that I decided never to trust old valves, NOS or not.
I stick with stainless steel on the street and titanium on the track.
HTH,
--Mike
.....ditto......


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