Vacuum Switch

[fred75]

  Any body have/ know the specs on these??? When trollin I see these black ones and red ones. Wondering if there both the same? I need a switch that opens a vacuum port at operating temp. I also wonder if any of these will close or open a port at operating or a different temp?

3053331 is stamped on top.  The ports are labled from top to bottom; M  HV  2  1
Came off a '84 350 in a C-10

[fred75]

 Ported Vacuum Switch L ENG CODE,EFE - 4 PORT - BLACK - 110 DEG FULL OPER TEMP - OE #3053331
1984 : GMC : G1500 VAN RALLY : 5.7L 350 cubic inch V8 4BBL (L) OHV : Electrical-Switch & Relay : Ported Vacuum Switch

[Lt.Del]

The TVS on my '79 5.7 Big 10 was orange.  When i put in my 383, I asked for a new one at the local parts store and got a black one.  Works fine for me...don't know if there is any difference.

[fred75]

The TVS on my '79 5.7 Big 10 was orange.  When i put in my 383, I asked for a new one at the local parts store and got a black one.  Works fine for me...don't know if there is any difference.

  Hey thanks for the reply. Got a chance to do a little more research and for some reason they are offered in different colors. I think your right, I don't think there is any difference. This truck did not come with any vacuum controls and when I saw these I saw a solution. Looks like I'll have to do some experimenting to figure out what the ports do and when... I have a bunch of emission schematics to look at that might give me a clue.