found some more info

Intake valves are typically made of martensitic (iron bearing/based) steel - this is why they are magnetic. Thus they tend to be more ductile at room temp that exhaust valves. The ductility makes them REASONABLE candidates for straightening.

Exhaust valves are typically made of austenitic (non magnetic) steels. In this case, they delete the iron and replace it with nickel or chrome or other alloys that give it much better HOT strength. For this reason, exhaust valves tend to be a bit more brittle when cold

No certainly not new... not at all, stellite is basicaly a cobalt-nickel or cobalt carbon steel alloy isn't it (can't remember)?

But íts new(ish) in valve technology.

<edit>....errrr scratch that,,, not that new in valves either... newer than mini's but not that new

from wiki-
Composition

There are a large number of stellite alloys composed of various amounts of cobalt, nickel, iron, aluminum, boron, carbon, chromium, manganese, molybdenum, phosphorus, sulphur, silicon, and titanium, in various proportions, most alloys containing four to six of these elements

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

The rocker cover is back on and the car is ready for a tune in the morning. But please carry on with the discussion, I like all this talk of alloys and unobtaniums very much.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

haha,, well I remember 2 of them

I nearly said Chromium, glad I didn't


It looks like most tool steels.


Got to say though.... WHY? wouldn't it be cheaper to do them in S/S than exotic steels? S/S might be a bitch to machine, but it would do teh job more than fine and its got to be cheaper?

ah,, who am I to question these things

good too hear its all back in one piece again
davo, i too have had enough freddo frogs and cherry ripes, and so have all the other boys at work
just as a side note all the valves (both inlet and exhaust ) that we carry for both mk1 and mk2 1275 heads are the stellite type
cheers josh
miniimports

There will be many extra typos over the next few weeks from our fat fingers scrunching all the keys up

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

SS is pretty soft, usually. And does not wear well. Stellite is a hardfacing alloy, it's hard stuff, and some grades are used because they have a low coefficient of friction against steel. For example you don't usually make complete valves out of it- just use it on the wear faces (like the valve face and end of the stem).

[edit]
example: Stellite 1 (which we used at work)
% composition:
Co: bal
Ni: max 3
Fe: max 2.5
Al:
B:
C: 2,45
Cr:31
Mn:1
Mo:
P:
S:
Si: 1
Ti:
W:13

Specifications:
Stellite 1 is a hardfacing alloy possessing high abrasion and corrosion resistance for applications such as pump sleeves and rotary seal rings, wear pads, bearing sleeves and centreless grinder work-rests. Retains hardness at temperatures in excess of 760°C (1400°F). Also available as thermal spray powder, JK 7201.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

So that's the bronze-ish colour that stains the metal on the ends? And no, the one I took off did not have this...

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.