355 header adn valve guide question

The valve guides were made of a material that just was not up to the demands of a modern motor and the heat they generate, The valve guide is a cylindrical piece of material the acts as a guide for the valve and allows it to move up and down in perfect alignment with the valve seat so that when the valve closes it lands perfectly on the seat in such a way that the machined portion of the seat and valve join and seal the combustion chamber. When the valve guide gets loose the valve no longer lands squarely on it seat thus no longer assuring a perfect seal every time causing power loss, rough running, oil consumption etc.


The most common failure on the cats is poor running causing overheating and a break up of the cat matrix which is made of a ceramic material and is very brittle. The cats also had another problem. The matrix is held in the housing by a wrap of a stainless steel mesh material that allowed for the thermal expansion of the ceramic matrix. This stainless steel wool if you will would often migrate out from around the matrix and allow the matrix to rattle around in the cat housing and eventually break up and go downstream depositing matrix material in the muffler and causing rattles throughout the exhaust system.

 

Just in case you are interested in buying an F355, here is the info. I have on when the factory changed to the longer-lasting sintered steel valve guides. Starting with assembly no. 27689 (visible on a small plate on the driver side of the engine compartment) the factory started using the sintered steel guides. This was mid-way through the 1998 model year so the vast majority of F355s were produced with the bronze guides, although some of them have had them replaced.

 

Also the cats are somewhat cheap to replace with Hyperflows which are much better designed and last forever. So don't let that scare you away. Most of the problems people talk about with the 355 are from people who have a friend of a friend who said somebody they knew had a 355 and it was expensive. If you are thinking about buying one, go to a local meeting of Ferrari owners and ask the people standing around the 355's.

 

If you want to see what happens to the headers, I have photos of mine:

http://snipurl.com/10st0

Basically Ferrari/ANSA used a cheap grade of stainless which can't stand up to the heat of the 355 exhaust. Over time they melt and crack. At best, your car just sounds like a VW. At worst, my understanding is that you can burn a valve by sucking cold air into a hot exhaust valve through the header holes. Mine went south at about 13k miles.

I had mine re-done by QV London. They cut out the existing pipes and just use the end plates. Then they weld in new tubes of a higher grade stainless. My repaired units have been fine for another 13k miles so far. The clean cuts are ones they did, but in the photos you can see how the tubes melted and perforated. Only my passenger side unit was bad, but I had both redone to be sure.

 

Rifledriver.....Great, informative response

 

CGPerry....wow. Cannot believe that is an oem part from Ferrari

 

HHHMMMMM---My car has a Nov. 97 build date, but the Assembly number is 28134...

 

I think your car is well within the latter "model year"

 

I clicked on the link and was amused to see that you can get a picture of your melted header tube printed on a coffee mug. I just might.

 

Excellent 355 Info from Tony : http://www.ferrarichat.com/discus/messages/256120/256560.html?1054899989