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Discussion Starter · #1 ·
I've had the manifolds off my car and am reconnecting all the hoses. This little widget appears to be a vacuum advance check valve, as one side is marked DIST and the other CARB. I can find nothing about it in any documentation. Was this a factory part? My car was sold new in California in case the makes any difference.

I'm assuming it goes on the advance rather than the retard line, but if anyone can confirm that it would be great as I forgot to note which of the two hoses it came from.

IMG_20200616_170539504.jpg
 

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Opel Rallier since 1977
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Dunno what year you have but in a '71 FSM, it refers to the advance side on the distributor diaphragm connecting to a port on the carb, and the retard side connecting to a port on the manifold. So if this is marked 'CARB', then that seems like it wold be in the advance side.

Is the vacuum connection diagram in the engine bay long gone? If you blow/suck on this device, does this always allow some air to move back and forth in both directions but slower in one direction (like a delay device)?
 

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It goes on the advance side. They were used to hold the vacuum so the advance stays in low vacuum situations like snapping the throttle open at low RPM.
 
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Can Opeler
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It goes on the advance side. They were used to hold the vacuum so the advance stays in low vacuum situations like snapping the throttle open at low RPM.
Surely it’s not a check valve. Wouldn’t that mean the vacuum advance would always be maxed? That would be very bad. It’s probably more like a delay valve. So it lets the vacuum decrease more slowly but still let’s it go back to zero.
 
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Discussion Starter · #5 ·
Surely it’s not a check valve. Wouldn’t that mean the vacuum advance would always be maxed? That would be very bad. It’s probably more like a delay valve. So it lets the vacuum decrease more slowly but still let’s it go back to zero.
That's what I was thinking.
 

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Discussion Starter · #7 · (Edited)
Sucking on it from the carb side of the valve my sense is that it lets low pressure through without restriction, but it starts to restrict more as you increase pressure. If you suck on it hard (get your mind out of the gutter, haha) as if you were drinking a milk shake through a straw it restricts almost completely.

I don't have any emission stickers on my car. Being a 1970 I'm not sure it ever had them. I'm guessing this valve was a California emissions thing since not many people here seem to know about them.

I might try running the car without it to see what happens. Looks like it could work on my yard as an emitter for my irrigation drip system too, lol.
 
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