Umm, does anyone has such installed? Did cars came with that or was it only option to some areas?

Green books says that if one connects hoses wrong it leads to increased fuel consumption. It also states that it is B19/B200 equipment, yet I have never before heard from one.
It is page 119/120 depending if you look pdf page number or number printed on page.

I don't have such connecton at air filter box either, at least I think so, but green book does not state it to be any special equipment.

Yes, I have, see http://www.volvo300mania.com/forum-uk/v ... 62&start=0
But it is not connected, and hoses are just connected with a tube

nekto wrote:Yes, I have, see http://www.volvo300mania.com/forum-uk/v ... 62&start=0
But it is not connected, and hoses are just connected with a tube

Ah, so it is then B19 motor feature of some sort. It should ventilate float chamber of carb, so valve should be open only at certain moments to not affect fuel pressure, which in turn would make car use more fuel. If it is all the time open, fuel will disappear from float chamber and car would be more difficult to start. It should be visible in wiring schematics of B19 motor then, maybe green books electrical section would reveal more.

the three way valve isn't electrical operated and standard on all 300 series B19A models

it is a really really basic valve that allows outer air to vent the floaterchamber, but anywhere above idle, the floaterchamber breather is closed.

the B200k has an integrated floaterchamber in the Cisac carb, mechanically operated with the throttle valve rod

Interesting, but what are those two wires for then? Some signal to something?

jtbo wrote:Interesting, but what are those two wires for then? Some signal to something?

As far as I understand, those 2 wires are for opening this valve. When ignition is ON, valve is closed and float chamber connected to air filter. When ignition is OFF, chamber connected to air to ventilate it and prevent high vapor pressure..
Not sure, but this is according to electric schematic..

yeah you are right nekto i was having a sleep-o

the constant-vacuum carbs can be quite annoying in terms of working principal