Can anyone explain the operation of the thermostatic vacuum switch on post
1972 TR6s? I have heard it described as an anti-run on valve, but there is
no connection to the ignition, so how would that work?
As far as I can tell, the valve switches the vacuum to the distributor (TRF
vol 1, page 99). Presumably this disables (or perhaps enables) the vacuum
advance until the engine is hot. This looks like a method of improving the
exhaust gases from a cold engine and should have no effect when a hot
engine is shut down. It may also be there to improve cold starting.
In the case of the post 1974 TR6s (TRF vol 1, page 100), there are even
more vacuum lines from the valve. They connect to the top of the carbs; I
have no idea what they do.
Trevor Jordan
74 TR6 CF29281U
|