<VV> Cylinder head temperature switch

[Dave Keillor]

525 for the "regular" cars, 575 for turbo, 140 and AC.  It's seems clear
that GM knew that the high performance engines (turbo and 140) had a
tendency to overheat.  They discovered this, no doubt, during
pre-production testing.  The logical thing to have done would have
been to >improve
the cooling, but that would have cost time and money.  Instead, hey took
the cheap and easy way out, and simply increased the actuation
temperature of the snap switch from 525F to 575F for those engines
(and AC cars).
If 575F is a safe operating limit for the high performance and AC cars, why
isn't it safe for the other cars?  It costs money to use two different part
numbers.
>The use of a 575F snap switch is, in my opinion, one of the reasons for
the high rate of dropped seats in the 140 engines.  You can run your 140
just below 575F for long periods and for multiple cycles and never know
it.  The turbos at least had a CHT gauge.  525F is unreasonably high, but
575F is very high.  Clearly, GM knew that the high performance engines ran
hotter, but felt that setting the over-temperature indication just short of
meltdown was a satisfactory solution.


Dave Keillor

On Wed, Mar 2, 2016 at 10:29 AM, Jim Simpson via VirtualVairs <
virtualvairs at corvair.org> wrote:

> Other than the mounting threads, what is the difference between the
> "regular" Corvair cylinder head temperature switch and the Corsa
> (140/turbo) head temp switch?  I seem to recall claims that they operated
> at different temperatures (the Corsa version being higher), but I can't
> seem to find anywhere that's documented.
>
> Anyone know for sure and where to find it?
>
> Jim Simpson
> Group Corvair
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