It all depends on which port on the carb you have your vacuum advance hooked up to. If you have it on ported vacuum (which is where common smog designed distributors run), then there won't be any vacuum coming from that fitting until the throttle blades open. But if you have vacuum advance at idle, then you're drawing from manifold vacuum, and the vacuum level will start to drop as the throttle opens. Which one you have the advance hooked up to will affect off-idle performance, as well as idle speed.

 

When my uncle was showing me how to check the vacuum, he was mainly checking the port on the front right (when facing the car) however there were two other ports that had vacuum as well, all of which had vacuum at an idle. Are all three supposed to be hooked up? we plugged the one on the front right and tried to run without it. It lowered my idle in park, so we adjusted the carb enough to keep in running while in gear and had the same problems.
We advanced the timing we retarded the timing, we fiddled and adjusted to our hearts contents and nothing seemed to make any difference. When we turn the idle up and rev the engine we hear a knocking sound that can only barely be heard otherwise. The car does burn oil and I have no doubt that it has been run out of oil in the past. Someone suggested perhaps the lifters are bad.... could that cause these problems?

As far as cleaning the carburetor, I really don't see that helping. As far as I can tell it was clean when we put it on a few months ago and seems to still be clean now (although I'm sure it would require tearing apart to be sure) and it would seem a coincidence that both the old and new carburetors have the same problems.

 

If you have a Holley carburetor, the vacuum port for the distributor advance is on the front passenger side, coming out the side of the metering block above the idle mixture screw.
If it's an Edelbrock carb, the vacuum port is on the front towards the passenger side, next to the bigger PCV valve port.
If it's a Quadrajet carb, the vacuum port is on the front towards the drivers side, above the idle mixture screw.
Under normal idle circumstances, those ports won't have vacuum coming from them while the engine is at idle.
Also make sure all other vacuum ports are capped off if not in use, and you don't have any missing/loose/split vacuum hoses anywhere.

 

Okay, so I definitely need to figure out what kind carburetor I have.
Aside from that, all three ports do have vacuum coming from them at an idle.... So how do I fix that?

 

Google each carb to see what they look like, they are easy to tell apart. Your carb would have the name cast into the body of the carb too. Some of those vacuum ports may or may not get used. The bigger center ones would get hooked up to your pcv valve, and power brake booster. Any others that aren't used need to get capped off or you'll have engine runnability issues. Go to AutoZone and pick up some vacuum fitting block offs. They look like short rubber hose tips that are rounded and closed off on one end. You can also use a cut off piece of hose and shove a screw in the open end, but that looks ghetto.

 

Okay, just googled those three, looks like a quadrajet to me. I also found this "Quadrajet also has an excellent bore configuration, with small primary and large secondary bores," so if Quadrajet is the only brand with that configuration, thats got to be it. Again, Im back in NY now, so I'll have to take a look for the name when I come back home next week
So my uncle was correct in checking the vacuum on the drivers side. But this also brings up another point... my choke, only the small primary ones open, are the larger ones supposed to be open as well? Now that I think about it, it seems like a silly question, obviously they're not just there for looks. But my point is, I've never seen the larger ones open.

 

larger ones are the secondary's and are open when throttling up. like 3/4 throttle or more. and you can get spread bore (small primary, large seconday) in carbs other than quadrajunk.

 

You're not going to "see" the secondaries open when you work the throttle by hand. Those open while you're driving, once you mash the gas pedal to the floor, and by as much as the engine's vacuum draw demands it. They're not mechanical secondaries.
You might want to make sure your choke linkage is working properly. There is a lock out pawl that prevents the secondaries from opening if the choke isn't all the way open (or if that linkage is stuck). The upper butterfly for the secondaries is held closed by a wind-up spring, and that butterfly also raises the secondary metering rods as it opens. If the spring is set too tight, it won't open. Set too loose, and it'll open too fast and flood the engine. Read the attached service manual covering the sections that cover these adjustments.
http://www.oldcarmanualproject.com/m...20complete.pdf

 

Okay, I'm going to be back home tonight (hopefully) I'll put up some pictures and try to figure out what brand the carb is by tomorrow.
That service manual seems like a foreign language to me but I'll work on trying to sift through it.
Also.... my neighbor has a 327 he is willing to sell me for $200 so I'm thinking about changing out the entire engine.

 

It's a Rochester quadrajet.