Vacuum Advance Distributor...Port Vacuum or Manifold Vacuum?

[1-ton]

It has been a while since I have owned a carbureted vehicle with a vacuum advanced distributor. I have forgotten if the vacuum advance on a distributor connects to port vacuum or manifold vacuum? I think I remember it being port vacuum, but I am not sure.

 

[sled_dog]

port

 

[1-ton]

Thanks.

 

[diesel4me]

both ways on some years......

Most Chevy motors used ported vacuum,but some during the emission years used maifold vacuum--I've swapped mine around,and didnt notice that much difference,ported seemed a little more peppy,so I left it that way--only way to tell which works best for you is to try it both ways,and see how it runs...