I ain't lars but there are 3 choices
ported
straight all time vacuum
no vac advance at all.

generally vac advance gives you more efficient cruise timing for better burn, cooler temps, mileage.

ported takes away efficient idle because no vac at idle

 

Is the ported vacuum you are talking about the fitting coming out of the manifold with the two tubes on it? If so where should the tubes go? To the carb? Like I said still learning about this vacuum stuff.

 

mani hookups are full time vac.
on a carb, generally, nipples above throttle plates are ported.
below, full time vac.

 

Allen,
What he means is, on Holleys the metering block, which is sandwiched between the fuel bowl and the main body have a vac port. You have yours hooked up there.
It's also called "timed vac port". It's for emissions. It also kills on performance you may desire. Just cap it off with a rubber nipple, not needed.

Your distributor vacuum canister should be connected to Full Manifold Vacuum. Your choice where to accomplish that. All those manifold ports have the same amount of vacuum. Some carb base plates have an extra port in the front or tap into the Intake itself. But never use the P.B. line.

 

See photo. Is this what you're saying? What is P.B. line?

 

Got it: P,B, Line. Power Brake. In the photo below the PB line, headlight vacuum and the plugged line are all going to one manifold port. Should the PB line go to a dedicated port and the others go to another one? Is this what you're saying? I DO APPRECIATE ALL THE HELP. I want to get this right and learning as I go along. Also, LARS stated my carb was very small. Do you know what the proper size would be for this engine?

 

Lars mentioned where to look for the carb number. Get of a picture of this and we can hopefully determine what carb size you have:

"...and FYI - the carb list number is stamped right into the choke airhorn on the forward driver's side.

Lars"

 

Looks like 6R8025 B

 

There's a steel line connected a hose from the lower front of the carb in your picture - where does the other end of this go? In my experience this steel line runs between the distributor vacuum advance and the carb but yours isn't using it that way. The only other thing I can think of that needs vacuum on that side of the engine is an automatic transmission modulator. If this is where the steel line is going, plug the trans vacuum into the hose with the bolt and run your distributor advance off the steel line, leaving it where it's already connected to your carb.

 

I'm beginning to suspect there is not a number on the airhorn. Do you see anything at all on the vertical sections of this part?

 

looks like stock cast iron,,spread bore.
allen, do yourself a favor and find an appropriate rochester
someone can give you the number to look for

 

Might have found it. 80457-7 0067

 

That steal line goes down the front of the firewall I assume to the trans.

 

Holley 80457 info. 600 cfm carb which is probably ok if it's working fine. Just hook up all your stuff appropriately.

https://www.carburetion.com/CarbNumber.asp?Number=80457

 

Here's a port diagram from a Ford forum .

Where it says "timed spark vacuum source", that's ported vacuum. While technically correct for as-delivered, it is not best practice for your car. Your car will idle terribly without vacuum advance at idle. Connect the vacuum advance (directly, no Tee) to the "Full Manifold Vacuum" port, and move whatever else you need to somewhere else (it looks like the manifold port behind the carb is capped for some reason?)

Email @lars for his timing papers. You should be able to pick up a bunch of performance from some simple adjustments.

 

Actually, the stock factory Q-Jet is 750 cfm, so the 600 cfm carb is a severe performance downgrade over the stock setup... But it can still be made to run nicely when correctly set up, and it should run trouble-free and reliably if correctly tuned with a good carb and timing setup.

Lars

 

I see now... the steel line from the trans has been straightened out a bit. Connect that to the manifold Tee with the bolt in the hose. Then connect the hose that was on the trans line to your distributor vacuum advance. You'll now have full vacuum for both components.

 

Yes, PB should always be a solo, dedicated line. Any outside source of vacuum interference such as accessories could affect your brakes.
As to post 25, yes cap that unwanted "timed" port. Not needed.
Yes move that hose from the metering plate to Intake manifold port.
But first, swap the PCV Valve with the valve cover breather. Find a new home for that hose.

 

Probably good advice in general but, at least for 1972, Chevrolet thought it OK to have the PB booster and the headlight/wiper vacuum tank fed from the shared manifold T.

 

The 600cfm 80457 carb on a stock 350 is fine........
If the carb is leaking out of the sides of the baseplate like yours seems to......it is bleeding bad from the boosters.....there are three things that can cause this.
1) Bad metering block gasket on primary side, secondary side, or both.
2) Blown power valve. The Power Valve adds the equivalent of 8 jet sizes to the mixture during different situations and if blown will just add that much all the time. I
3) Clogged high speed air bleeds. If the booster can't draw air through the air bleed along with fuel....it will just draw straight fuel.....
All three of the above conditions create a "dribbling" from the booster down the throttle bore......when the engine can't use it, it just floods above the throttle plate and out the gap in the throttle shaft/throttle plate.....to the outside of the carb.
The 80457 does not have a secondary metering block and only a metering plate. These almost always bleed through if they sit without fuel for months at a time.
All your carb needs is a good refresh......AED makes a kit pt# 4160 that has everything you need. I would advise you to rethink the fuel inlet on this too......there are several ways to route the 4160 style drivers inlet to the pass side fuel pump......here is what I like to do:

Above pic has a 180 degree fitting as the air cleaner is not dropped base (1956 Bel Air)....dropped base air cleaner will use a 150 degree fitting......the -6 AN adapters at the carb end and fuel pump end are available from the major fitting suppliers.
The L-79 327 from 1965 to 1967 had this style carb on it from the factory and the reproduction fuel lines from a Corvette vendor can be adapted as well.

That is a circa 1990 Edelbrock Performer intake that accepts either square bore or spread bore carbs.

I disagree with this carb being a downgrade in performance as a stock 350 at WOT past 5500rpm will never utilize a full 600 cfm of flow. The Q-Jet 750cfm is an upgrade IMHO becasue of its tiny primary venturi to create super high velocity from its stepped primary boosters.....this for a make a snappy and efficient engine due to excellent booster signal and emulsion.....

I could pull this carb from that engine...bench it in three hours and have it back on the engine running proper........you can too!

Jebby