Aisan Power Valve Circuit (1 Viewer)

[mwebfj60]

Here's my understanding of the Aisan power valve circuit..
I borrowed a couple of these pics from another thread. Feel free to chime in and correct anything.

I suppose a good place to start is how the power valve operates..
In its resting state (out of the carb), or extended, the valve is closed...no flow through the valve. If you squeeze it together, the valve opens and you get flow through. Notice there is a jet screwed into the bottom.

 

[mwebfj60]

This shows the basic position of the power piston and power valve when installed in the carb

 

[mwebfj60]

Next step in figuring this circuit out was to determine where the vacuum that controls it comes from...the hollow bolt that holds the throttle plate to the carb body is the passthrough...the port is shown in the pic labeled 3

 

[mwebfj60]

If you follow the bolt up, you will find the holes the vacuum passes through in the carb pieces...the route can be verified by blowing air through each hole and finding the output

 

[mwebfj60]

So when you have vacuum higher than about 3" pulling through the hollow bolt, it pulls the power piston into its bore, the vacuum overpowers the spring. When the power piston is sucked in, it isn't pushing on the power valve anymore and the spring on the power valve keeps it extended so the power valve is closed.

 

[mwebfj60]

Once vacuum through the bolt drops below 3", the power piston spring pushes the power piston down, pushing the power valve together and opening the power valve. This lets additional fuel flow into the primary circuit.

View attachment 1457988

 

[mongoose2231]

That's a good hit of tech there, great work.

 

[mwebfj60]

So the question becomes when are you pulling vacuum through the port? It is underneath the butterfly valve so it's similar to a ported source. So suddenly flooring it should drop this vacuum and open the power valve.

 

[NeverGiveUpYota]

Proof mine is doing its job.... and now I've had the revelation that that is why that gasket is made of that type of material.

 

[NeverGiveUpYota]

So the question becomes when are you pulling vacuum through the port? It is underneath the butterfly valve so it's similar to a ported source. So suddenly flooring it should drop this vacuum and open the power valve.

Sounds about right. @Slow Left has done tons of carb sleuthing as well.

 

[mwebfj60]

Thank You! I was searching all over for that this morning. Ran across that a while back and took a pic. That's a great thread!