TVS

[steven d. ferguson]

Donald,
It is a smog device. It limits vacuum advance until the engine reaches
operating temperature, then allows vacuum. If you're stuck in traffic
or stopping after a long grade & the engine temp rises, it fully opens
and the increased vacuum advance raises the idle speed to help cool the
engine.
HTH,
Steve F.

 

[steven d. ferguson]

Dean wrote: Steve, I believe you are wrong. It does not limit vacuum
when the engine is
not up to operating temps. It only increases the vacuum when the temp
exceeds
the norm.
Dean
Sounds good to me. I also read somewhere that it allows manifold
vacuum ie; full vacuum, when the engine temp gets high.
Steve F.