What is this electrical vacuum device?

1980-1986 Datsun 720 forums. All 720-specific topics and discussion can be found here.
Posts: 12
Joined: Wed Aug 13, 2014 9:38 pm
Car: Xterra(s) (multiple), 720 Pickup

What is this electrical vacuum device?

Postby spddm0n » Mon May 06, 2019 11:50 am

Hi all -

I just purchased a 1985 Nissan 720 pickup and I'm working to get all the vacuum lines routed correctly and rebuilding the carburetor in order to pass emissions here, and I can't find any good diagrams to identify this device sitting on top of the inner fender liner (apron) inside the engine compartment, nearly underneath the silver data plate (attached to the passenger-side engine bay sidewall), and sitting on top of a small platform that is bolted to the sidewall.

I've seen a variety of other trucks and photos of other trucks and none of them seem to have this device. I Googled the numbers printed on the side of the electrical device, but nothing conclusive comes up.

Anybody know what this is and what the correct route of the vacuum lines should be?





Posts: 6
Joined: Sat Apr 18, 2020 7:30 am
Car: 1983 Nissan 720 4X4 Sport Truck

Re: What is this electrical vacuum device?

Postby Gr8Guyn08 » Sat Apr 18, 2020 8:52 am

I have a 1983 720 which should be pretty close to your 1985. I don't think that the valve that is in your photos is original and the reason that I say that is because of the mounting. I don't think the factory would have mounted something on the mounting bracket where you have to remove the bracket to get to the underside to remove the valve mounting bolts.
That being said my 1983 has a electrically operated vacuum valve in the same location. My valve is slightly larger and looks completely different but I believe that it is the same function. From what I can determine from the factory shop manual this is the Boost Control Valve.
I can't tell for sure where the vacuum lines go without taking the air cleaner off (which is a big job) but both vacuum lines have a "T" fitting located an inch or two from this valve. One side of the each "T" goes off under the air cleaner. The other side of the "T" go to two other electrically operated vacuum valves or possibly vacuum switches that are mounted on the side of the bracket this valve is on or maybe the wheel well.
Okay, back to the vacuum lines that go under the air cleaner. From photos that I took years ago I believe that one goes to a right angle fitting that is screwed into the top of the intake manifold. The other line I think goes to a small pipe that is on the (drivers) side of the carburetor.

Hope this helps.

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