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Re: [T3] ZZZZZZZippp

On 8 Mar 2001, at 19:51, Russ Wolfe wrote:

> Ahhhh, another point to bring up..... VW did change their valve seats in I
> think '68. The exhaust seats were changed to "Stelite" <sp>. This was about
> the time that leaded gas was going away. It was also at this time that
> cylinder temperatures started rising due to the leaner emission standards.

I've never seen mention of a change in the seats, but that doesn't 
mean it didn't happen. I've only heard the valve seats referred to as 
"hardened." I would think the Bill Fisher book would cover this; I'll 
look tonight.

Stellite is a cobalt-chromium-nickel-moly alloy that is used in the 
heads of exhaust valves. It's an interesting alloy: It can only be 
cast or ground; it can't be machined with cutting tools.  

If you have an old exhaust valve and a small magnet handy, it is 
VERY interesting to run the magnet up and down the valve. You 
will find some areas which are magnetic and some which are not. 
Depending on the brand there will be 2 to 4 different regions. It 
makes you appreciate all the work that must go into making a 
good valve, and explains why exhaust valves cost more than 
intakes. It may also be a way to spot a cheap valve. 

Jim Adney
Madison, WI 53711-3054

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