Vacuum switch??

[Edward Stills]

Can someone help me identify want this vacuum switch is for? I'm only guessing it's a vacuum switch because there's vacuum lines that come to it on both sides.

 

https://photos.app.goo.gl/Ha3FXys4pj7vmR5w5

 

1984 720

 

[Stoffregen Motorsports]

That's definitely a vacuum solenoid. They call them different things in the industry. VSV (vacuum switching valve) is the most common term.

 

Where does each end terminate? Knowing that would help you further identify it.

[Edward Stills]

That is the one of the reasons why I'm asking. The vacuum on the right side is just laying there open. The vacuum on the left side tees into vacuum line coming from the manifold to the brake booster/cruise control.  

 

The wires (Red/black & Black) just go into the harness. If I follow The red / black wire it goes to the terminal block  and then goes to the blue wire which goes to the 'E' terminal on the distributor module. No clue to where the black goes. (Edit: Actual the black goes to the negative battery terminal.) 

 

Vacuum piping (left side)

https://photos.app.goo.gl/TYxfHp9CRmrnKuG89

 

Wiring diagram 

https://photos.app.goo.gl/e1zs6snT7bX3UG336

 

Terminal block 

https://photos.app.goo.gl/8VvYtEZNfLfxusix8

 

Distributor terminal 

https://photos.app.goo.gl/YiYDgYktbhs8aNYp8

 

 

 

 

[720_Jeff]

That vacuum switch is for AC.  

 

 

https://www.nissanpartsdeal.com/parts/nissan-valve-assy~27680-03w00.html?vin=&make=Nissan&model=720 Pickup&year=1985&submodel=&extra1=&extra2=&filter=(1=K%2fCAB;2=Z24;3=ST;4=F5;5=LONG;6=2WD;7=CAL)

 

Edited July 15, 2022 by 720_Jeff

[Edward Stills]

2 hours ago, 720_Jeff said:

That vacuum switch is for AC.  

 

 

https://www.nissanpartsdeal.com/parts/nissan-valve-assy~27680-03w00.html?vin=&make=Nissan&model=720 Pickup&year=1985&submodel=&extra1=&extra2=&filter=(1=K%2fCAB;2=Z24;3=ST;4=F5;5=LONG;6=2WD;7=CAL)

 

Thanks!  Looking into it.

[datzenmike]

For the idle up solenoid on the carburetor. Increases the idle speed to compensate for load caused by the air con compressor when it switches on.

[Stoffregen Motorsports]

A quick google search for Datsun 720 engine bay shows that valve on Z motors, but some of the pics show it hooked up differently than others.

[datzenmike]

 An electric solenoid would have been much easier.

[Edward Stills]

1 hour ago, Stoffregen Motorsports said:

A quick google search for Datsun 720 engine bay shows that valve on Z motors, but some of the pics show it hooked up differently than others.

Yeah I found that too. Little bit confusing. I'm actually putting a Weber carburetor on it next week. Going to be pulling some of the vacuum hoses out. I do have AC and would like for it to be in the circuit. Maybe I can retrofit a electric solenoid. 

[Stoffregen Motorsports]

Check out what @Crashtd420made for his Weber side draft. It's a simple idle up solenoid which pushes the carb linage. Many V8 equipped domestic vehicles had them starting in the early '70s. Finding one that's compact will be the challenge. Maybe Crash can tell you.

12 hours ago, Edward Stills said:

Yeah I found that too. Little bit confusing. I'm actually putting a Weber carburetor on it next week. Going to be pulling some of the vacuum hoses out. I do have AC and would like for it to be in the circuit. Maybe I can retrofit a electric solenoid. 

 

[Stoffregen Motorsports]

12 hours ago, datzenmike said:

 An electric solenoid would have been much easier.

A vacuum solenoid accounts for more variables.

[Thomas Perkins]

Since I had my Weber put on mine,I plugged the hose that goes to it,it is for the A.C..That was long time ago.It is not used on Webers,they will tell you when you buy a Weber,but if you need one let me know,mine works and is still on my truck.You can find sites to rig something up or idle it up 1000 rpm.I have a new Custom made heating and air and he rigged it up to when A.C. is turned on,the idle doesn't go down.The fuse box is not used for my heating and air no more.He rewired it.I don't even have the Nissan blower motor or any other heating and air stuff,all gone.Can't find heater cores no more.