Ex Valve 308 sodium filled

As an answer on the thread of Lostbowl I can confirm that the number you have found on the exhaust valve of your car ( partnumber 106553 ) is only one of the possibilities.

This specific partnumber refers exclusively to a sodium filled exhaust valve, but this valve is used in a variety of Ferrari engines and not only on the 308 series engine.
These valves are used on the Dino 246 GT, Dino 308 GT4, 308 GTB/GTS, Mondial 8, BB512 and on the 400, 208 GT4, 208 GTB/GTS. The valves in the Dino 208 GT4/208 GTB GTS and the 400 are different in size compared to the 308 series.

The sizes of the exhaust valves used in the 308 series are all the above mentioned partnumber. There are also valves used in the 308 series with only symbols. They read for example EL BM ST FS. These valves are also sodium filled. (these symbols refer to the materials used in the valves)

The reason that there are some horrific stories on F-chat is that a lot of people don't have an idea of what is happening inside an engine. The main reason for dropping a valve is due to the fact that the clearance of the valve stam in the valve guide reaches a point where they should be replaces with new valve guides. Often the company who replaces the valves and/or the guides do only one thing: replacing only the valve guides without replacing the valve!!. The reason of breaking is due to metal fatique and nothing else.

For example: take a piece of iron wire and bend it a few times and it will break between your fingers. With a valve it is exactly the same, because of the valve clearance in the valve guide the valve closes not at once but in steps. People who really listen to an engine with worn valve guides can hear the rumble of the valves when closing. With this thread I also want to warn people that when they think of rebuilding an engine or the cilinderheads it is very important that they don't try to save money by doing only one thing instead of them all. So please people: if you want serious engine damage look at the pictures below. ( not for the faint at heart)

Ferrari is like any other automotive company not commited to only one supplier for certain parts. Because if one factory goes into bankrupcy production suddenly grinds to a hold. There are two well-known producers of these valves: TRW and EL (Eaton Livia).

The pictures you see were taken in our engine rebuilding shop. (www.westecmotoren.nl )
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