Valve guides.
- Thread starter jug
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In racing, if you over-rev and bend a valve, the bent stem strains the guide. Bits are likely to break off a cast iron guide and drop into the cylinder, damaging everything there.
A bronze guide is more likely to stay in one piece.
Bronze has better heat conduction properties than iron, but I'm not sure that it matters.
A bronze guide is more likely to stay in one piece.
Bronze has better heat conduction properties than iron, but I'm not sure that it matters.
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There are several different bronze alloys used for valve guides. Some wear out very quickly. [ie phosphor bronze matched with a plain steel valve]
Guides made of Ampco 45 or CDA 954 aluminum bronze will outlast iron guides and plain steel valves 2 to 1- when matched with a hard coated or chrome plated valve stem.
Cast iron guides will damage the hard coating on Black Diamond valves and usually cause a lot of valve stem wear.
Cast iron guides when used with a chrome plated valve stem [if you can find them] can provide reasonable life. Jim
Guides made of Ampco 45 or CDA 954 aluminum bronze will outlast iron guides and plain steel valves 2 to 1- when matched with a hard coated or chrome plated valve stem.
Cast iron guides will damage the hard coating on Black Diamond valves and usually cause a lot of valve stem wear.
Cast iron guides when used with a chrome plated valve stem [if you can find them] can provide reasonable life. Jim
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jug said:
Some cowboys do make them from brass, but they're rubbish.
Do you mean bronze?
I can confirm from first-hand experience that the original cast iron guides will outlast any bronze guide.
When I “Dunstallised” my 750 Norton, I fitted Dunstall’s own bronze guides to the head, these lasted less than 15 months compared with the 5 year old cast iron ones, so are NOT very durable and long lasting.
When I “Dunstallised” my 750 Norton, I fitted Dunstall’s own bronze guides to the head, these lasted less than 15 months compared with the 5 year old cast iron ones, so are NOT very durable and long lasting.
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I have had bad experiences with the bronze guides from UK when used with OEM valves back in the 70's and 80's. As I recall they were usually advertised as phosphor bronze. 10,000 miles and they were completely shot.
A little better was cast iron with OEM valves. The valve stems suffered though.
Better yet was cast with chrome plated stem valves.
Then I went to Kibblewhite Ampco 45 guides with Black Diamond coated valves. I find I can get at least 30,000 miles from them. Jim
A little better was cast iron with OEM valves. The valve stems suffered though.
Better yet was cast with chrome plated stem valves.
Then I went to Kibblewhite Ampco 45 guides with Black Diamond coated valves. I find I can get at least 30,000 miles from them. Jim
lcrken
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Bernhard said:
Correct. Dunstall catalogs referred to it as "Hi-Dural 5 (Reg'd)" or "Hi-Dural Five (Regd)". Phil Irving referred to it as "Hidural 5" and recommended it as a material for valve guides. Langley Alloys still lists HIDURAL 5 (also called HIDUREL 5) as an available alloy. They describe it as a proprietary copper-nickel-silicon alloy developed by them in WWII for high performance bearing applications, including main bearings in the Merlin engines in Spitfires. They also list valve guides as one of the applications for it. They describe it as having high strength, high thermal conductivity, and outstanding bearing properties. It's thermal transfer rate is three times that of phosphor bronze and three to four times that of aluminum bronze. Composition is 2.00 - 3.50 % Ni, 0.40 - 0.80 % Si, 0.05 - 0.30 % Mn, and the rest copper, with very small amounts of aluminum and iron. Langley is based in Staffordshire, but also has two locations in the US, so might still be readily available (or might not).
Ken
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Ken (or others),
Care to expound on the virtues of Beryllium Copper for guide material when compared to AMPCO45 and Hidural 5.
Care to expound on the virtues of Beryllium Copper for guide material when compared to AMPCO45 and Hidural 5.
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SHIT. When I rebuilt my engine a month or so ago, I fitted 2 new black diamond exhaust valves. As far as I can tell, it still has the original valve guides. Do I have a problem and should I remove the head and change the valves to some more compatible with the "cast iron" guides?
Dereck
Dereck
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kerinorton said:
You know the answer!! :shock:
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