Do pre 1967 Mopars have a ported vac advance port on carb, or did they just use manifold vacuun for the Vac advance. Thank you.

should be ported.

No mopar had manifold ported vacuum for distributor...wait for it..

What does this statement even mean?

I think he's waiting for a typical moparts argument to break out? I'm interested in the answer as well, I'm not old enough to remember when or if direct manifold vacuum was used. I_think_ported vaccuum started in the emissions era but don't really know.

Ported vacuum comes from a small opening / passage that is slightly above the primary throttle blades at normal idle opening IE: 750 or so RPM with no radical camshafts that require more throttle opening at idle speeds.

As the throttle blades begin opening during acceleration the air passing by the opening begins drawing air (vacuum if sealed of hooked up to a non leaking vacuum advance. This is known as the venturi effect. See pic below. the red indicates air flow, the blue vacuum. As the throttle blades are opened, more air passes by the port and the vacuum increases adding more advance.
So there is no vacuum available at idle speeds .


Manifold vacuum ion the other hand is highest when the throttle blades are closed ( depending on camshaft) as the pistons are trying to draw air/ fuel against a restricted opening (the throttle blades). However it drops rapidly on acceleration due to the throttle blades opening. As one reaches cruising speed and the blade opening in relaxed the vacuum then returns to a higher state.
Which is better? I'm not going to open that debate.
To my knowledge Chrysler used ported vacuum in most applications. That may have changed during the emission years. hope this helps

I started working in service stations in 1961, I remember a lot of the early GM cars had manifold vacuum advance back then, hence the disconnect the vacuum advance and plug the fitting instructions before setting the timing
As far as I can remember now all Mopars engines I worked on had ported vacuum advance, all of them

I know what ported vacuum is I just could not understand the comment as written, even if trying to be sarcastic. I do not know for all cars, but the Carter AFB pre emission were ported. I do believe that all Chrysler were like that as they had a different approach for emission/CAP for their cars at least in the 60 and early 70. So ported was not an emission thing. Chrysler chose to use vacuum advance to control timing on load, and chose to have idle run with no vacuum advance.

In the true cap years starting in 66 for Chrysler CA only. And 68 for all states, they did use the Vacuum canister for 4 speed cars to switch to Manifold vacuum during deacceleration only. Cars were tuned for lean idle and retarded ignition. Even the hemi starting in 68.

The info Cab furnished jibed with what I'd gleaned over the years. It seemed the older guys, the chev centric guys, all asserted manifold vacuum was the "correct" way to hook up vacuum advance to the point they'd arbitrarily change it to manifold on whatever car they were working on even if it didn't come that way. By the time I started my mechanic years (1973) mid '60's cars coming into the shop was a bit of a rarity, let alone earlier ones. At that time cars 5~10 years old made up the bulk of junkyard denizens which made parts for my '68 readily available cheaply.

Well my 51 Plymouth has ported vacuum stock

He is not asking which is best, just how did they come originally. So there really should be no debate, Chrysler used ported.

Were they still using hard plumbed lines then or had they gone to rubber hoses by then?

I think they where steel up to much later in the mid 1960, maybe even later

Hard line from carb to vacuum canister, as is the 52 Dodge 230 I bought to build and hot rod.

i'm not going to start a debate here. everything was ported up to around 74ish [?], then, if i REMEMBER correctly [???] there were trees on the rear of the intake manifold that went to a vacuum "enhancer", then to a temperature sensor in the water pump housing, then to the carb, then to the distributor and vacuum pots controlling the air filter snorkel flaps.
i just looked at a 440 out of a 78 newyorker, and a 400 from a 76 newport [both with thermoquads] that are on my shelf, and that is the way they have the myriad of vacuum hoses ran. they were this way when removed, and i just left everything as was just to keep the holes plugged.
i "think" this started in 74, because i remember the round multi-port "vacuum enhancer" on the china wall of my wife's 74 charger with a 400/727 combo.
remember, this is for the big blocks. i don't remember, nor have, any small blocks to compare.
so manifold through temperature [wax pellet] senders to ported.
i don't know what this setup could be correctly categorized.

Short answer is yes there is a ported vacuum connection on carbs before 67. I have a 62 383-2bbl, and a 62 413-4bbl both have it done in rubber hoses. 1960 413-4bbl has it with a hard steel line.

The OP specifically asked about pre 67. Why bring up the newer stuff?

because it was stated previously that there was never manifold vacuum used.
your point could also be used about 30's and 40's engines, as well as the steel and rubber lines.
i was just offering a little more to the story, sorry if i rubbed you the wrong way.
please accept my apology.

Wait for all the know it alls (keyboard jockeys) to claim otherwise.

Not for distributor advance

Still ported vacuum not straight, all those connections were used so engine got to operating temp first. Look at the advance ‘can’ on a mopar distributor. They ALL pull the plate in the timing advance direction so IF it’s manifold ported it would be in wrong direction, give it gas it drops, let off it advances, backward! Chevy was like that, had one, 70-1/2 Z28

Pretty sure you don't know the difference between manifold vacuum and ported vacuum.

Also pretty sure you don't understand why vacuum advance is used.

Pretty sure you’re an a$$, I know exactly what I’m taking about. Do YOU know what manifold vacuum is? Do you know what carb port ABOVE and BELOW the throttle plate is?

Your not serious are you? So what is it for if not distributor? I don't know why you would trash a thread for kicks with mis-information, clearly you are wrong in your statement. But why? That 66 hemi of yours has ported for the distributor.

Trash the post huh! Well let’s see, The ignorance on here is astounding. I’ll make this as simple as I can. ANY ‘port’ above the throttle blade goes to distributor, PORTED VACUMN, Any port under the throttle blade is MANIFOLD vacuum, and goes to something beside the distributor. If your not at least 70 you didn’t live first hand with this stuff like I did. When you work for Dodge you get to go to all their tech schools and I went to learn from the experts.
Done

That is not what your post were saying so.....the confusion of your post. The Master training lectures are on the web so any one can look them up. Once the throttle blade is opened the ported position to the distributor is activated and the vacuum at that port is almost the same as the manifold vacuum off the intake, or the PCV port at the back of the carburetor. Basically an on off switch to prevent any vacuum advance from being applied at idle with throttles closed and high engine vacuum.

So as stated Chrysler used the ported (Vacuum Spark Port) on the carburetor for the distributor vacuum advance. The vacuum advance was used to adjust timing to account for the motor load, while the mechanical advance account for the speed of the motor. Carters only had one vacuum port sized for the distributor.
Holley's did have more on the throttle plate, but as far as the time frame discussed predominantly Carter AFB and AVS for the 4 barrel cars as explained above.

I know exactly what manifold vacuum is.

I know exactly what ported vacuum is.

Now tell us what manifold ported is, your terminology.

Hello, I have a question related to manifold vs. ported vacuum for the vacuum advance. I know it's not directly related to this thread. But I have a 67 R/T with a 440 that has a Speed Pro cam that's 300/300 at the seat 230/230@.050, 109 LSA and .480 lift. With the vacuum advance hooked to the ported connection(factory) port on the carb the idle is somewhat choppy. I was advised to connect the vacuum advance to manifold vacuum, which I did and this really cleaned up the idle. I almost forgot to mention that I have a six pack setup on the car as well. Does anyone see a problem with using the manifold vacuum for the vacuum advance with this setup? Thanks everyone!

Pic

Not an expert, I think what's happened is you've added a bunch of initial timing through the vacuum advance and disturbed the operational RPM range aspects of the vacuum advance. I'd put it back to ported, to the center carb metering block and go back and add initial timing to see if the idle stays "cleaned up". 2¢

Thanks for the reply. The initial timing is at 10 deg. before, without the vacuum advance hooked up.

Wow. Maybe I'm a cynic but if you have to tell someone the PCV port is not for fuel, they may be better off owning a Prius.

When you put in a bigger cam you generally need more initial timing to clean up the idle. You did that by switching from ported to manifold vacuum. Adding initial timing also does this but then you may have too much total advance and you may have to recurve the distributor to reduce mechanical advance. If it idles good with manifold advance give it a try. It may work but as you open the throttle manifold vacuum drops and you will loose timing so it may not run well. If you get spark knock then you'll have to get into the distributor at which point you should go back to ported advance and start from there.

Good luck.

Thank you that sounds like good advice.

Ha ha, You're absolutely right. But you can bet Edelbrock was getting complaints from some people that their carb was flooding due to them having the fuel line hooked to that port. Plus, they have to protect themselves from the lawyers that sue over everything.

Ok I just had to go look at the 64 AFB on my 65 Corvette. It does not have ported vacuum. Yes I know it's not a mopar but what chevy does is use manifold vacuum to increase timing under idle and light loads as a way to run more advance for better cruising and better gas mileage plus allowing for more mechanical advance.
My factory distributor has 22 degrees mechanical that comes in early and when you add vacuum under low loads you have at least 35 total advance and closer to 40 cruising. But when you accelerate fast you lose vacuum and therefore retard timing so the engine doesn't knock.

Just the opposite of Mopar.