Valve guides.

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jug

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Any advantages for bronze valve guides over cast iron. Apart from the expansion qualities of the different metals ???
JUG
 
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.
 
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
 
Thanks Jim, and you other guys. Running JS black diamond valves (with his beehive kit) so brass is best for these? Cheers
JUG
 
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.
 
Bernhard said:
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.


See my post above concerning different bronze alloys and valve stem materials. Jim
 
Bernhard said:
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.

My experience is the opposite. Original guides in my 74 850 smoked in 3 years, about 7500 miles. Replaced with bronze and got 15 years from them.
 
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
 
Bernhard said:
Dunstall guides were made, if my memory is correct, from Hi-Dural 5 material.

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
 
I suspect the secret to getting good life from Bronze guides is the valve stem treatment.
Hard coatings such as chrome , DLC or Nitroneg coating on Black Diamonds -do work well. Jim
 
All the reports of Commandos with untouched motors with big mileages under their belt are with cast iron guides.

??
 
Rohan said:
All the reports of Commandos with untouched motors with big mileages under their belt are with cast iron guides.

??


There is no question. All untouched motors with high mileage have cast iron guides....
 
If itchy to spend to max out advantages consider cyro temper valve and dry friction impregnate guild and stem.
 
Chilled cast iron comes with the ultimate impregnated 'dry lube' = graphite flakes ...

Thats why millions of engines for a century or more ran unlubed iron guides even, and they lasted and lasted....
 
Rohan said:
Chilled cast iron comes with the ultimate impregnated 'dry lube' = graphite flakes ...

Thats why millions of engines for a century or more ran unlubed iron guides even, and they lasted and lasted....

Why is it that every Norton cylinder head I see with over 10,000 miles on the iron guides and OEM valves have very worn guides? - Not to say they wouldn't run that way for a lot longer if you don't mind the noise or performance loss. Jim
 
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
 
kerinorton said:
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

You know the answer!! :shock:
 
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