Doug,
Apologies if you already got an answer.
On my '72 the effect of the switch is to speed the engine up (I assume
this comes from the change in timing) and therefore cool the engine down
when idling in traffic for long periods of time. In an indirect sense
it is for emissions. In normal temp operation the timing is diddled
away from optimum to cut emissions, this causes the engine to heat up.
The valve does it's thing, the timing changes to optimum and the engine
cools off, etc. etc.
It works very nicely and you should keep it in service.
On mine I also found seemingly no action under any circumstance when
testing, but it does work. I don't understand the reason for the vapor
pressure of water part of your question. The action of the switch can
be compared to the temp compensators on the carbs. As the temp goes
up/down a bi-metal (my theory, no backup) strip opens and closes a
vacuum port.
While I said mine worked it took several tries to get it hooked up
properly. Mine has three ports one of which is not used.
Steve
Subject: Thermostatic Vacuum Switch
The real problem is this
I tested my switch in hot water as you'd do with
a thermostat, but I couldn't get that puppy to move at all. Stamped into
the
capsule end is "220," but that can't be the opening temperature (water's
vapor pressure at 2200F is almost 18psi).
I can't find a source for a replacement switch, so I reckon we need to
fix
this one... hopefully without de-crimping the assembly.
Question 1: Do I understand this thing correctly?
Question 2: How big a hammer does one use to free-up a stuck
thermostatic
capsule?
Doug Morris, '74 TR6 CF18kUO, NC
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