Let's start with pics. I wanted to figure out what the X port's purpose was so had to cut one in half to investigate. The FSM diagram showed a pretty good pic of it below.
The VCV (1 Viewer)
- Thread starter mwebfj60
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- #2
This is my take on it.
When no vacuum is applied to S, Y holds vacuum. X and Z have some airflow between each other. The only thing connecting the upper and lower sealed chambers is the shaft that the diaghragm pulls and the stopper is attached to.
When these things were new, was that sealed up or was there a designed intention to have X bleed into the top chamber when there was no vacuum applied to S?
It seems like X is there just to provide vacuum relief from the diaghragm chamber as the diaghragm pulls or retracts.
When Vacuum is applied to S, X will hold vacuum and Y and Z flow freely between themselves.
When no vacuum is applied to S, Y holds vacuum. X and Z have some airflow between each other. The only thing connecting the upper and lower sealed chambers is the shaft that the diaghragm pulls and the stopper is attached to.
When these things were new, was that sealed up or was there a designed intention to have X bleed into the top chamber when there was no vacuum applied to S?
It seems like X is there just to provide vacuum relief from the diaghragm chamber as the diaghragm pulls or retracts.
When Vacuum is applied to S, X will hold vacuum and Y and Z flow freely between themselves.
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- #3
This is Y and the spring and stopper disk.
The top of the X chamber/bottom of the upper chamber, shows the shaft passthrough.
The top of the X chamber/bottom of the upper chamber, shows the shaft passthrough.
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- #4
There are 3 separate sealed chambers...upper where Z and Y feed in, the middle where X comes in, and the bottom where S is plumbed. The thing separating the bottom and x chamber being the diaghragm itself. The top chamber is a solid molded piece with just the hole for the shaft.
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- #5
Some other angles
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- #6
A few more
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- #7
No vacuum on S, large spring pushes the diaghragm and shaft up, pushing the stopper against Y.
Vacuum applied to S, diaghragm and shaft pulls down, the upper spring pushes the stopper down onto the hole and seals up X in the process.
Vacuum applied to S, diaghragm and shaft pulls down, the upper spring pushes the stopper down onto the hole and seals up X in the process.
It is a vacuum operated vacuum switch... nice dissection!!!
Pipe X is the breather for the back side of the pipe S diaphragm chamber. Without a pipe X breather, the diaphragm can't move and the valve won't work.
Amazing dissection! I always wondered what was inside those.
Amazing dissection! I always wondered what was inside those.
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- #10
I agree with that logic for X.
That makes me wonder what the vacuum coming from the air cleaner port to the distributor VCV is. If I wasn't disassembled doing a water pump I would throw the vacuum gauge on it to see if it registers anything or enough to warrant an X.
That makes me wonder what the vacuum coming from the air cleaner port to the distributor VCV is. If I wasn't disassembled doing a water pump I would throw the vacuum gauge on it to see if it registers anything or enough to warrant an X.
