Heat riser and vaccum

[Conrad]

I have a dodge 360 2bbl in my clipper.  What I think is the heat riser is linked to a vacuum diaphram mounted on my carb.  The vacuum source is via a little electric vacuum switch mounted just aft of the vacuum amplifier.  The amplifier provides the vacuum source.  While replacing some vacuum lines I experimented with that diaphrams' vacuum line.  Moving it to a different port on the electric switch, the diaphram was actuated, lifting the 'heat riser' link up and kicking up the idle a notch.  I noted that my vacuum reading at idle increased to around 20"mg (notation?).  

"This is good", I say to myself.      

My question:      Is this the correct hookup for my heat riser?  I always thought that a heat riser was just a coil spring device used to divert warm exhaust gas under the intake manifold plenum thereby helping to vaporize the air fuel mixture during cold starting. If so, why the vacuum link?  If not, what's going on?

[handyman]

In later years the old spring system was replaced by a vacum operated system witch was a lot more reliable the system works off a heat switch normaly when the engine warms up this switch opened and ported vacum to the valve to open it or on some systems it was the other way around it had vacum at cold and none at temp if it was working before let it be the system was great