Just read through the thread to help in diagnose my lack of center vent issue and I tested 1-4 on the vacuum block and 1 and 2 do not hold, 3 holds and surprisingly 4, center vents, hold.

I didn't do the rest of the ports because I was stumped why my center vent would hold vacuum. I pumped it to 5" and visually inspected that it was open and holding.

So I put the line back and started the car and put it on EC, temp wheel to min, and fan to high. No center vents.

Puzzled I tested how much vacuum was coming into the 7 port block. At idle its 9" of vacuum and then I decided to test it in the engine compartment, 9-10" vacuum there.

How much vacuum should I be getting at the supply for that vacuum block? I do not think I saw the value anywhere in the 13 pages.

thanks