73 CUDA vacuum fitting port intake manifold

[Ralph]

I just completed my winter project - replaced dash pad, dash harness, rebuild ac / heater box, restored instruments etc.
I got everything going except the heater setting to go to the floor it always comes from the vents same with defrost. Checked the vacuum out of the small hosing fitting on the manifold and there is barely any vacuum. I cleaned it but still not much vacuum. Motor rebuilt with good size cam.
Can anyone tell be what vacuum should be coming out of this small fitting - by the way the power brakes work fine. (same fitting)
I changed the push button heater / AC switch which had a crack in it.
The heater box was restored by a very reliable source who rebuilt everything including checking all the hoses and actuators.
I was thinking to hook it up to the carb fitting which has more vacuum to test it.

Any help would be welcome
Thanks Ralph

 

[Steve340]

All vacuum sources provided they are connected to the intake manifold will have the same vacuum reading or should do.
This reading will be whatever vacuum that particular engine has.
It may be your tubes. If the tube is a soft rubber with a little hole in it the vacuum may be sucking the tube shut. Possibly, hard to know but worth checking. Vacuum hose needs to be very resistant to collapsing.

 

[Ralph]

got it, will check into this

Thanks Ralph