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+--- Thread: Valve guides (/showthread.php?tid=6265)
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Valve guides - Robert Foreman - 16-06-2021
Has anyone used a different valve guide from the standard cast iron ones?
RE: Valve guides - Ruairidh Dunford - 16-06-2021
I had bronze (I think), inserts fitted years ago but they did not perform any differently - what are you thinking Robert?
RE: Valve guides - Robert Foreman - 16-06-2021
Manganese bronze guides.
RE: Valve guides - Ruairidh Dunford - 16-06-2021
They could well have been that, they are still in the Ulster [sic]...
It was quite a bit more expensive than simply replacing the guides and they have worked no differently.
RE: Valve guides - Robert Foreman - 16-06-2021
But have you measured them for wear to compare with cast iron?
RE: Valve guides - Ruairidh Dunford - 16-06-2021
Of course not!
RE: Valve guides - Ruairidh Dunford - 16-06-2021
They’ve done about 60k without issue, but so have the standard ones in the Chummy...
RE: Valve guides - Tony Betts - 16-06-2021
the only thing that would bother me with bronze, is like everywere else a bronze bush is used with a steel shaft.
it doesnt seem to reduce wear, it just wears the steel part instead of the bronze.
nothing to worry about in any short term, but may need keeping an eye on in the long term.
tony
RE: Valve guides - Howard Wright - 16-06-2021
Hi All
Tony’s comment struck a chord. I’ve recently refurbished an FZ22 carb. I was expecting to have to bush the spindle but it turned out that all the wear was in the steel spindle and the carb body was as good as new. A friend suggested that the bronze/brass acts like sandpaper with grit embedded in it.
Cheers
Howard
RE: Valve guides - Hedd_Jones - 16-06-2021
Experience with steam bearings over many years has taught many of us that if using 'bronze' of unknown provenance (i.e offcuts from the scrap yard) often the shaft needs to be hardened to prevent issues. But particularly also with any of the 'PB' bronzes.
Preferred material is SAE660 (Leaded Bronze) if carving from solid, or One of the 'LG' leaded gunmetals if using castings. LG2 often. These have proven to be fine with the normal steels used by us for shafts. EN8. EN16, EN24 EN40 etc, there is a tendency for owners to use stronger and stronger steels, where EN8 is better than original spec.
It machines better too, machining some of the PB bronzes is like machining snot.
That said, I have no idea what a valve is made from, it might be hard enough for PB.