Got myself an 70 318" Power Wagon.
Someone put a 4-bbl Eddie on it with an AFB 9636S 625cfm carb on top. Have no idea of internals but you can hear it has a little more cam. Runs pretty good actually but you can hear it's more in it. Was guessing slow advance curve and rich jetting so I started from scratch.
Put my gauge on the right hand vacuum port but there was zero. Hmm... tried the left just in case but same result. Sucked myself on the gauge and the needle moved. Put it back on the intake manifold port (right) and gave it gas and the needle started moving a little! What? Pulled the hose from the PCV-port and engine instantly died.
All I can say is that this engine makes a lot of vacuum, can tell from the suction off the PCV hose when it came loose.
Didn't have much time and and had a coolant leak so I stopped there.
What is going on??

the port on the passenger side is for the vacuum advance, the opposite port is for EGR. Both are "ported" ports, no vacuum at idle as the origin is above the throttle blades.

don't think it's an Edelbrock carb you have there, 9636 comes up as a pushrod set for Edelbrock.

Probably a Carter Competition Series AFB 9396S.

According to the info I have the small nipple closest to the linkage is full time vacuum, the small nipple closest to the choke is ported vacuum.

Link to the Edelbrock carb manual, shows the same as the Carter as far as which nipple is what

http://old.edelbrock.com/automotive/mc/carburetors/pdf/carb_owners_manual.pdf

you're correct. the nipple next to the linkage is full vacuum. ported vacuum is above the throttle blade (passenger side), full vacuum is below the throttle blade, (driver side). no vacuum from either says something is screwed up.

This was a universal replacement / performance type carburetor. Note the two small nipples either side of the PCV, both are ported vacuum, the right for vacuum advance, the left for EGR, note 50 & 51.. Also note the electric choke and vapor return line.

Go look at your PDF, it shows the nipple on the linkage side (#51) as FULL TIME VACUUM, not ported. Number 50 in your PDF is listed as Ported Vacuum, exactly as I said.

A simple visual also confirms the vacuum sourcing for either nipple, below the throttle shaft is full time (#51) and above the throttle shaft (#50) is ported.

i have a lower body from one of those carbs laying around and got looking at it. I know now why the port on the throttle side would/could be used as a timed port. the port is at the throttle blade, not under it. this is unlike the edelbrock carbs where the port is below the throttle blade. definitely could create some confusion due to the different locations of the tubes. anyhow, there is a small cup plug under the port passage that could be removed to create full manifold vacuum. whether the small rectangular orifice would need to be plugged or not i'm not sure.

That's an ERROR. I had one, The OP CONFIRMED there's no vacuum at idle on either port. it's a universal carb, EGR does NOT use full time vacuum. And yes I know that, carb 101. Look at the pic of the actual carb, both on the same level.

They are not on the same level.

Sorry for my slow action. You are correct about AFB 9396S, my bad, but that's exactly what I have.

Next thing is drivers side port. Exactly as you say it should have full time vacuum as it looks to be located under the butterflies. I does not. It has the same vacuum as the port to the left and that made me totally confused.

Anyway, I used the big nipple in between (for PCV valve) and solved it that way. 12 in hg in D by the way.

I will have the drivers side plugged and use the one on the pass side for distributor vacuum.
But I'm still confused...

Thank you soo much for bringing the light to this mystery!
Next thing I wanted to do was to remove that freaking carb and look at it but since you looked for me I don't have to

The only little mystery remaining is why they made them that way?

Calm down gent's!
Look, my carb look very much like the one in the pic. It has the text Carter AFB - Competition Series though.
It has the electric choke and the vapor return nipple (hose is not there anymore)
It has the two nipples 51 and 50 - but none of them gives a vacuum signal at idle. The drivers side nipple sits lower than the pass side nipple and that why I started this thread, I was confused