sodium valves

The place I got my ss valves and brass guides, and was told they are the best, is S I Industries in Simi Valley, Ca. (805) 582-0085. Intake and exhaust were $22.00/valve, and guides were $7.82/guide

 

I've used SI in the past and was pleased with the products. If you get SS valves, make sure they have the hardened tips!

 

The sodium valves have these markings written on the tip (just above the keeper groove): "EL BM ST FS". If its different, you can check by running a magnet along the stem (its not magnetic, but the tip and head are). Most likely they've never been changed. Its a very good idea to replace them, replace the guides while you're in there too.

I got my valves from Superformance in the UK. Stainless with tufftrided coating and stellite-welded tips and valve-seat rims. Inexpensive.

 

Wasn't the sodium used to help with heat issues? Did it turn out to just be a bad idea?

 

Sodium turns into a liquid just above room temperature. When in liquid form, it has high specific heat so it can be used to absorb heat at the combustion chamber and transfer that heat to the valve guide much more rapidly than steel. Thereby reducing the temperature that the steel outer casing has to endure*, and combustion chamber heat also. However, the remaining steel is thinner and is subject to somewhat higher stress (there is less of it--and the same amount of spring seat pressure), so the valve streches and can break with less than optimal consequences.

*Regular steel exhaust valves transfer most of their heat to the cylinder head through the valve seat. This puts a minimum size for the contacting ring to transfer the required amount of heat.

 

So did Ferrari stop the sodium valves on later models?

 

Yes,
I've forgotten the specifics, believe when they went to fuel injection, but could be wrong. At this point in time, the sodium filled valves are getting pretty brittle and should be replaced if a head is being pulled.

For lots of details, go to 'Old FerrariChat.com Archives' topic and use it's search capability at the bottom of the page. Several good threads last spring.

 

I want to think my 84 308 has sodium valves as well (4 years into fuel injection). Anybody know?

 

What came up with your archives search?

 

The real reason for sodium-filled valves was because of the air-injection. If you take a look, the injector nozzles point straight at the valve heads. Air injection obviously supplies ambient air to the oncoming exhaust gas and this helps to oxidise the Carbon Monoxide and turn it into less harmful/polluting Carbon Dioxide. This process creates incredible amounts of heat and therefore needed the extra cooling affect of the sodium in the valves.

No air-injection, no need for sodium-filled valves.

 

Peter,

While your argument is logical, in the thread below JRV was pretty adamant that only 2V engines had the sodium filled valves. He claimed that the 4V valve stems were too thin to be sodium filled, and Ferrari was already having embrittlement problems with the 2V engines.
Also has a pretty graphic description as to how fragile the sodium filled valves have become!!!:

http://www.ferrarichat.com/discus/messages/256120/302519.html

Perhaps Dr. Ferrari, Dave, or another of the professional mechanics can comment also.

 

I think a different explanation is in order.

The sodium filled valves are for 2 V heads. When Ferrari when to 4V heads, the valve stems became too thin to allow drilling and filling with sodium.

 

Verell, I'm not arguing the fact that QV's had sodium-filled valves, I knew they didn't already and I do remember that thread you posted...

All I said was a reason why they used sodium in the valves and I implied it to the 2 valvers since this was what this thread was about. Sorry if I was not specific. By-the-way, I'm familiar with how brittle the valves are, I've seen a broken one and the damage it did. Ain't pretty.