Possible cause/relief for header/valve guide problems???

Thank you for taking the time to type that up, very informitive and makes sense.

I'm not a mechanic of any sort, not even on the internets type. lol

 

Ok, bronze is pretty resistant to heat. I say something in the design of the valve train is rocking the valve stem back and forth to distort the valve guide.

 

Actually the Ferrari guides are "copper alloy". Stated directy from the 355 service manual. I'm sure they have a bronze content too, but to what ratio, I don't know. All I know is they are very, very soft compared to the manganese bronze I use.
When machining the factory guides, you can tell in an instant that they are very soft. Small valve stems don't come into play, Honda and Toyota among others, use smaller valve stems than 355's.

 

Absolutely NO rocking taking place on 355 valve stems. The cam tappet pushes directly straight down on the valve tip.
It is in no way like a small block chevy, with a rocker "sweeping" the valve tip

 

no idea why...i can only imagine it's the crap material that people say it is.

i rebuilt the whole engine though....thought i may as well.

it has the original headers, which have been welded. last time was 5 years ago.

 

Pure and simple, the stock valve guide material SUCKS.

 

Does the F355 engine use oil squirters and would this have kept the valves cooler, besides the pistons? Porsche has been using them since the 917 possibly earlier to cool the pistons.

Many years back I had blown two motors (one Japanese one German) due to high duration racing cams stretching the original guides beyond spec bending the valves, hence my question.

 

Ok, read this: http://www.ferrarichat.com/forum/showpost.php?p=74762&postcount=1

Turns out it was improperly seated valve guides.

 

That was Ferrari propaganda and was disproved years ago.

 

Don't hold back.

 

Are you familiar with the inside of a piston engine? The valve guides are a long way from the pistons and in any event are cooled by their direct contact with the head.

 

Hey Brian, I was curious if we could maybe talk about headers, valve guides and all the rest of this BULLS**T maybe just one more time....



Here are a few thoughts that come to mind when
I read this header stuff for the 1,000,000 th time.......
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I did some analysis on a sampling of valve guides from different Ferrari's, thanks to Dave Helms for providing them. I can't support the 'material sucks' theory, the original 355 guides have a higher hardness than any other that I tested (note the Rockwell 'C' scale starts where the Rockwell 'B' scale maxes out)

http://www.ferrarichat.com/forum/showpost.php?p=136907134&postcount=109

Also note that it is actually pretty rare to use steel for a valve guide. I'm no mechanic but my casual observations at auto shows of engine cut aways and talking to other OEM engineers confirms that some bronze is normally used. It seems that Ferrari changed to steel because their first choice of material couldn't handle some operating condition, like perhaps heat.
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And a picture of the guides...
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355 valve guide material did suck. By your logic the same materials used in the Wright Flyer would suffice just fine in an F22. Sorry but the F22 put just a little greater demands on the materials.

Time marches on. Combustion temps, exhaust temps, and specific HP have risen by leaps and bounds and the materials used did not. Then take into consideration the 5 valve head has a miniscule amount of cooling water around the valve guides and seats because there just isn't room. The wearing area of the tiny little valve stems needs to be considered too. As pointed out, bronze of some alloy is fine, just not the trash Ferrari used.

Sorry but the material did suck and any assesment needs to take into account all those factors.

As for steel being rare, Detroit used its low rent cousin, iron, quite successfully for several decades in millions of motors that gained reputations for the longest lasting gasoline motors in the world.

 

I never thought I would see monkey wood and valve guides in the same thread, you could be on to something here, maybe the reason the valve guides suck is they are made of monkey wood!

 

I never thought I'd see a valve guide thread again either.....

I'll bet your right they are made of monkey wood!!!

Headers must be made of Weasel wood! I probably should not post that until the kids go to bed.....


I wonder where enginefxr is hiding?

 

Step away from the monkey wood!

Just wondering, with the whole technology marching on theme what are the 360 and 430 valve guides made of? If anyone has a used one laying around for some reason (or a 355 steel) send me a PM, I'd be happy to do the same analysis to see what's going on. Still looks to me like the 355 guides were better than anything Ferrari had used before, they just weren't 'enough better' to handle the higher rpm and smaller valve stem.

Surely someone on Ferrarichat must have factory contacts who might talk off the record to set us straight? If not I'll step up here, Ferrarichat can send me to Italy and I'll ask

 

F@#%ing water heater!!!!

Anyway.....
I found the box that the supplier used to shipped the 355 valve guides to Ferrari.
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I just laughed Diet Coke through my nose. Thanks a lot.

 

Sorry, Daniel.
I think we've made Helms ruin 2 or 3 computer monitors/keyboards in the last few months!

 

5 valve head: http://www.billzilla.org/20vhead.jpg
4 valve head: http://www.billzilla.org/16vhead.jpg
of Toyota's 4age engine...notice the 5 valve's cramped spaces and smaller valve guide channel

 

Iron

 

I have tried my bypass wired open and factory setting. With the bypass in factory setting, the rear challenge grille is noticable hotter to touch after a drive compared with the valve wired open. I didn't do any observation re:exhaust tips, but I know I have to wait about 15-20min after a drive to put the car cover on with the bypass wired open because the tips are so hot.

For the moment, I have wired it open due to the following reasons:

Its not too loud (has a tubi muffler)
It seems to accelerate better (very important)
I get the 355 sound at 3000rpm without have to 'floor it'
No bypass rattle

 

After a long search I found out who decided to use the material in the 355 valve guides...Interesting as he is also the lead designer of the 348
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