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Original Message
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| The "steel" guides are actually cast iron. |
| By Dave Shoe - 02/07/2004 12:19:38 PM; IP 216.243.176.34 |
Steel would be a horrible guide material, and you won't find any made of it. Cast iron is a good, long lasting guide material. Just as it works in the cylinder walls because of it's large content of graphite, it also works in valve guides. Bronze is preferred in some performance applications, but I'm not sure why. I believe bronze doesn't lubricate as well as iron, and it does not last as long, but it is more forgiving under hard racing conditions. I'm presently just guessing - I seem to recall that I knew the distinction between iron and bronze guides, but I've not thought about it in a while and I've forgotten the distinctions. I used to think cast iron was inferior until learning of the lubricity of cast iron.
The cam was not particularly radical for the valve train. Still, the 2-piece rotating valve retainers of the stock engine are not at all capable of handling high-lift performance applications, and they may have been taxed a bit hard. Is there any indication that the valve retainer smacked into the valve guide or the valve seals? What condition were the valve seals in on the good cylinders? If O.K., then I suspect the valve retainers may have been fine for that application.
A more pressing issue with valve guides is typically proper reaming to size. I'm not a hotdog with this issue, but there are folk who understand the dos and don'ts of reaming and sizing guides.
I've got too little knowledge of the condition of your entire engine to be able to offer a logical failure path. I wish I could help more, but lacking sufficient info, I cannot determine whether this was "just one of those things" or whether it was a builders mistake.
If you post more details which describes a very complete picture of your engine and the symptoms which lead up to the rebuild and failure, I may be able to offer more opinion, and with luck may even come up with a logical conclusion to the failure. I do enjoy failure analysis.
As for cast iron rings: I've only used moly filled in my rebuilds, so I don't know all that much about them. I will say that all top rings are typically made of nodular cast iron and all second rings are typically made of gray cast iron. Again, the lubricity of iron-on-iron is excellent, topped only by the layer of moly-disulfide. Chrome rings lubricate poorly, but they are really abrasion resisitant and good on rougher cylinders and dirty environments. I can't imagine problems running plain cast iron rings in an FE with a good air cleaner. I believe factory rings were plain cast iron (nodular and gray), but would have to check to be sure. What cylinder wall issues are you seeing?
I'm confused by the "piston parts" you described. Did the piston fail and cause valve problems, or did the valve fail cause piston problems? You description is missing some critical pieces.
Shoe. |
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