Well can't say they were steel the first time, just read they had to do it 2 times. Sent using FerrariChat.com mobile app
^^^ Can't agree more. There are a sh** ton of smallblock Chevy's out there right now that came from "batches" of bad valve guides that now have 150+K miles on them and are doing fine. NOW-- if one were to do a leakdown test on them, (and then automatically assume bad guides) then holy cow there would be a worldwide shortage on valve guides!
Well, here is my two cents.You do a leak down. If it turns out bad based, on what ever limit is acceptable, and traced to valves, the valves aren't seating correctly. PERIOD. Could be guides, build up, or some other reason. You can add all the fuel cleaner you want. Leak down may improve. But that doesn't address the underlying issue. You need a valve job to do it right.
Never seen build up to any degree on exhaust valves in the 355. Exhaust temps so high it keeps it burned off. Intake valves on the other hand it is pretty common. Have seen a large ball of build up on back side of valve head it prevents closure. Bottom line is if leakage is from exhaust side 99% of the time it is valve guides. If from intake it is typically carbon build up. That is the condition that from time to time we hear of an Italian tune up making a difference.
We have replaced nearly 100% of the exhaust valves and about 50% of the intake valves on the heads we have done. Its not always just stem wear. By the time you have the faces cleaned up the heads can get too thin. Also with a stem that small there is very little surface area to wear and not that much of a wear limit. None of this stuff was designed to last forever. If you build it like a stationary diesel power plant it will run like one too. You ought to see the Kleenex parts the F50 engine is made from.
355s were a substantial leap in engine output. Engine management technology allowed for a large leap for everyone. Ferrari made the mistake of continuing with some earlier material technology that were no longer viable due to mostly the combustion and exhaust temperatures then being experienced. That was why manifolds burned up and why the old bronze guides were no longer good enough. The stuff that worked in 308, 328 and 348 was no longer good enough.
Nope but if it is not landing on a proper sized and shaped seat or has a guide that prevents it it cannot cool and that will be the outcome. And that does not take into account all the other possible causes. Another problem with those heads. The valve stem sizes and seat sizes were smaller than most local machine shops were equipped to handle and those sizes also required much more accurate work. Many got rebuilt because it was the local guy and he was not experienced enough to say no. Many were doomed to fail when they were reinstalled. Its not like doing a V8 with .375 stems and 2.00 valves.
Do you know how many miles are on this head since last removed? The surface is really clean and looks like not long since it was resurfaced.
no it can’t lol. It would be nice to have more context on whoever’s engine this is. What was the actual cause. Rifledriver has a good point, the head could’ve been worked on prior that caused issues, not every machinist is capable of replacing or reaming the guides. Another cause to add is also cracked exhaust headers that overheated the exhaust valve. A picture can say a thousand words or asked a thousand questions. Depends who’s looking at it.
There may have been a few thousand miles on that engine since the first valve job done by a dealer (I don't know who).
So another example of heads done more than once. Drove my heads up to Olsen Engines in NY for mine. Sent using FerrariChat.com mobile app
Here in the tri-state NE many dealers and Indy shops send them our to Olsen Engines. It takes heavy expensive machines and not everyone in front of a mill can use it correctly. Experience counts in this area. I serious doubt dealers do it them selves. Sent using FerrariChat.com mobile app
Very few if any. Used to be SOP. When I started in this business every shop I worked in we did our own. It got harder and harder to hire people who could do it and became impossible to hire people who could do it profitably. No one even surfaces rotors anymore. Many do not do transmissions in house, manual transmissions. Shows level of knowledge and competency in industry. My machine shop comments regularly on how few shops they are able to communicate with on specific technical issues. People wonder why I work alone. And they call themselves "Technicians".
So you know how hard it is to find a decent machine shop. Spent years developing good subcontractors in California and there is a huge well developed car culture there. Moved to Texas and everyone ****ed up everything I gave them. Finally bought some Pelican cases so I could ship everything back to California. I could ship an entire V12 in Pelican cases. I could not ever get a flywheel resurfaced properly locally. In an F1 it is important and I have learned more about resurfacing flywheels and the machines that do it than I ever wanted to know. One reason so many shops are just selling new flywheels. One of the 2 shops I used on the coast decided to retire during covid. He was 70 something and just called it quits. ( I am not far behind him). Finally went to a place out in farm country about 70 miles from here one way. His primary business is hot rod Cummins diesels. But, again he's in his 60's but he gets it. When I describe what I need and why he doesnt wonder why. Once I explain he understands and better yet he can do it. My old starter alternator guy just retired too. I have to find a new one of those now. Should be simple but I have had too many cars get stranded 200 miles after a fix to agree it is simple.
Funny you mentioned that because Olsen Engines has been doing them it 50+years and about every Ferrari, heads blocks, racing motors everything, he is 70 as well and is retiring in the early spring. I got in under the wire.
Are there shims for each valve like the 348 ? It's possible it was incorrectly shimmed at the last maint. Valve appears to have been burning for some time due to inadequate clearance ?
Just released today, Normal Guy Supercar Ferrari chat sponsor Daniel Hurlbert and Josh from Exotic Power & Performance are once again working on the Ferrari F355 engine rebuild project. Valve guide time….
Did they add commentary on how they had to sell part of the liver, I know they had to sell their kidney to work on it the first time, you know because Ferraris are so expensive to work on and even a simple belt change cost 25k. Sent using FerrariChat.com mobile app
Well, nice update. My heads are FINALLY back! the valves ended up being just fine. The guides were not. Hoping the car goes back together without any further issues!
