<VV> 'Hour-glass' head screws?

[Hugo Miller]

A clutch head is a 'one-way' security screw that you can tighten but 
not undo. What are those weird 'hour-glass' head screws on the 95? I've 
just been wrestling with some of them while changing the throttle cable 
on my Corvan. I had to grind down an Allen key to undo them. Luckily 
they weren't too tight nor corroded in place. Why would they use such an 
unusual head - I don't think I've ever seen them before?

On 2020-01-02 02:43, FrankDuVal via VirtualVairs wrote:
> I have not been into a heater switch. Should be similar to other
> switches, like the windshield wiper or turn signal of an early.
>
> Fillister is the shape of the head, tall like a Rochester carburetor
> screw or a "cheese head" screw.
>
> 
> https://www.google.com/search?q=fillister+head+screw&oq=Fillister&aqs=chrome.2.69i57j35i39j0l6.3257j1j4&sourceid=chrome&ie=UTF-8
>
> The hourglass drive is a "clutch head" design.
>
> 
> https://www.google.com/search?q=clutch+head+fastener&oq=clutch+head+fastener&aqs=chrome..69i57j0l7.4482j1j7&sourceid=chrome&ie=UTF-8
>
> Commonly found on the interior sheet metal of a Corvair 95. And
> inside the Powerglide.
>
> Frank DuVal
>
> On 1/1/2020 3:35 PM, Smitty via VirtualVairs wrote:
>> Ole weak eyes.  Closer examination of the fasteners holding the fan 
>> switch into the heater controller showed that they were Fillister head 
>> fasteners.  You know the ones with the hour glass drive in the head.  
>> Now we are talking my language.  I got a piece of seat spring wire and 
>> ground a tool to fit.  The screws are out.  Now all (ALL) I have to do 
>> is fix the switch.  Anybody been into one of these?  Any advice.
>>
>>
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