gamma series 2 vacuum advance valve

[keri]

Hi to everyone i am looking for help with understanding how the ignition vacuum advance switch works and how to test its operation.
It sits on he front slam panel next to the right hand under bonnet light it has 2 electric connectors and 3 ports.
the electrical connectors i assume turn it on/off to allow vacuum to the advance unit from engine?
the pipe from the engine goes in one side and the opposite port goes to the distributor then the 3rd points down to the front x menber with no pipe attached is this correct ? maybe an exhaust port? how does this valve work and how is it tested just want to make sure its ok before refitting
many thanks
keri

[Theo]

I have spent a lot of time trying to figure this out and I believe I've got it. But I have seen a lot of Gammas with the vacuum valve piped different to mine so people must disagree (or maybe there's different valves?).

I believe the purpose of the valve is to allow for vacuum advance to take place up to around 2400RPM. Above that engine speed, the vacuum pipe to the advance mechanism is cut off and the centrifugal advance inside the distributor takes over.

When I inspected the valve on my car, one of the 'ports' was blocked. Not blocked by the valve but the plastic 'port' had no hole in it. I therefore ignored this port and concluded only the other two should be connected. And that is the two at right angles. A lot of Gammas I have seen have the two pipes connected at opposite ends of the valve. They must either have different valves to mine or they have them connected wrong.

To test the valve, at 'rest' i.e. with no power to the valve, blow through the top port and air should come out of the port at the other side at right angle to the top port. Once you provide 12V to the terminals, the valve will close and the airway between the ports will be blocked.

To test the electronics, connect a voltmeter to the terminals and rev the engine to about 3000 rpm and you should have 12 volts at the two terminals.

Please ignore the different position of the valve in my engine and the strange radiator but I have a non-standard radiator fitted to my car so the vacuum valve was also relocated but it should show the connection of the pipes and wires. The top pipe is the vacuum pipe from the manifold and the other pipe goes to the distributor vacuum advance mechanism.  

[keri]

Thanks again for your help with this i will be on it in the morning to see whats happening
just looking to get it right as it is all going back together so making sure all is well
thanks again
 Keri

[keri]

Thanks Theo
tested the valve worked as you said so was connected wrong originally so worth while doing
thanks again
Keri