Author |
Message |
Biknut
| Posted on Thursday, September 30, 2004 - 12:05 pm: |
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nallin heads use bronze manganese valve guides. won't these type of guides have high wear compared to iron. iron guides seem to last for ever. can anyone tell me about their experience? |
Bluelightning
| Posted on Thursday, September 30, 2004 - 01:19 pm: |
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I bought a set of the bronze manganese guides from Nallin to put in my re-worked X-1 heads. I was originally under the impression that they would keep everything slick and hence reduce some friction. While the do that very well, you are right that they wear out faster. The shop that set up my valves told me that the iron guides worked very well on the street, and that the bronze manganese guides are best suited to the track where engine tear down and rebuilds are a common thing. |
Rocketman
| Posted on Thursday, September 30, 2004 - 09:46 pm: |
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We use to use bronze guides in our Triumph 9 and 10 stud splayed heads years ago, in place of the old iron guides. The iron guides had a habit of breaking in those days. They wear too you know. I've seen plenty that were worn oval inside the guide bore. Rocket |
Biknut
| Posted on Thursday, September 30, 2004 - 11:48 pm: |
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thank you for the replies. |
Pammy
| Posted on Saturday, October 02, 2004 - 02:18 pm: |
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Myth: Bronze guides don't last Fact: Early, silicon based, bronze alloys used in valve guide applications, quickly earned the rep of having poor wear performance. When high nickel based, bronze alloys (AMPCO 45), were introduced, the valve guide market was able to offer a superior bronze valve guide suitable for high heat applications. Cycle-Rama uses manganese bronze alloy guides. The alloy should be called 'zinc bronze alloy' instead of manganese because it contains nearly 30% zinc and 2-3% manganese. Manganese is the hard part of the alloy and the zinc is the bearing ingredient which is a material that is also a self lubricant. For stock replacement, cast iron guides work fine. However, the problem starts with the high performance applications. In higher lift applications, the guides need to be shortened. With more heat(typically)and side load from the valve involved, the oild film between the valve and guide deteriorates quicker. In addition to increased viscosity breakdown, cast iron guides are also an abrasive material which induces the premature wear that we're used to seeing with this application. Also, in cases where the valves(for whatever reason) may collide with each other or with the piston, cast iron guides have been found to fracture and deposit damaging fragments into the cylinder and combustion chamber. This is not the case with manganese bronze guides. I hope you read(and understood) that BEFORE you fell asleep! I was nodding off myself! |
Biknut
| Posted on Saturday, October 02, 2004 - 09:38 pm: |
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thanks a lot pammy for that informative info. |
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