Vacuum diagram - Lettered ports? Valve functions?

[simplesimon]

I'm trying to understand the vacuum diagram under the hood of my 1/2 Chevy van. It's a Canadian 1986 Chevy C10 half ton van with a 4.3l V6 engine and automatic overdrive transmission.

Vacuum diagram: members.shaw.ca/mystuff/New%20vacuum%20diagram.gif
Vacuum schematic: members.shaw.ca/mystuff/vacuum.gif

I've got a few questions:

- What are all the lettered ports on the carb?

- On the various valves in the diagram, which ports are controls? Which pass vacuum?

- Where can I find a schematic for the EFE/DIST TVS and EGR/Purge/TCC TVS?

Thanks!

[idol]

Hi Simon, maybe I can help.
Question 1, the letters don't really matter as long as you have an accurate diagram. If you were using a factory build diagram, then you'd need to have knowledge of the letters. I can see you have a good diagram, if you use that it should help you check and maintain your system.
Question2, simply stated, anything on the carburerator side of the valve will be vacuum and and once activated anything opposite the carb side will be doing work (or in some cases passing vacuum)

Question3, from my review of the schematics you have provided you should have all you need to manage and maintain your vacuum system.

My question to you is, do you think something is missing from the schematic that you have under your hood (an unknown part) or are you have just trying to get a better understanding of how the system works?
Please lets us what more you'd like to know and I'm sure me our my colleagues here can help you..................................IDOL02