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Vacuum Switching Valve

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So I’m in the process of doing a emissions delete on my 620 (every bit of it was rusted and all the vacuum lines were shot). This is a 1979 Datsun 620. In the process of deciding what should stay and what should go I found there’s a switch mounted to the top of the EGR manifold with two electrical wires and a vac line coming in looping into itself and coming out it’s body. I had to do a lot of digging because I couldn’t find it listed in my manual or on here but I found a manual that had it. The vacuum line coming off the carburetor and feeding into the vacuum advance splits off into the VSV and goes somewhere from there. Can anyone explain the purpose of the piece to me and if I need to keep it attached. I just want to make sure it doesn’t interact with the distributer.


Vac switching valve: https://imgur.com/gallery/vaxgxiN

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 You can leave it or remove it. If disconnected, be sure the open T on the vacuum advance line is sealed. 

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Are there electrical wires to it. The picture doesn't show it.


As one of the hoses goes to the air filter it can be assumed that when the valve is open air (filtered) is allowed in destroying the vacuum advance signal. No vacuum advance. When valve is closed vacuum advance is allowed.

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