Yup .... and .... fuel is a coolant for valves. Running lean is a
valve-burner.
bob

On Sun, May 24, 2009 at 12:32 PM, aatransaxle <daryl@aatransaxle.com> wrote:

> Now mind you this is going way back into my brain...and correct me if I am
> wrong of course...
> Doesn't the valve transfers it excess heat when its actually closed for
> that
> brief time that it's not open???
> When the valve is open, the only way to transfer the heat is thru the valve
> stem..
> If thats the case, a tight valve never seats onto the valve seat and
> crystalizes the stem just below the head.
> Thats the way it was taught to me in the early 70's when broken valves were
> the norm on aircooled engines...and why we adjusted tham so religiously
> every 6000mi
> Still happens that way I would think, but not near as much as the
> watercooled motors run much cooler head temps.
> When overrevving, the valve spends less time "seated" and more time open,
> hence less transfer of excess heat. That and when it suddenly starts being
> seated and banging on the seat harder, any stresses may make it pop off the
> stem.
>
> Daryl of AA Transaxle
>
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