Vacuum Port Connections on Edelbrock Carb

[60Lark]

I am new to this forum, but not to Studebaker Fever. I have a 1960 Lark Regal VIII with 259 engine with flight-o-matic transmission, no PCV valve. I replaced the Carter WCFB with an Edelbrock Carb a while back and I thought I did it right, but I have been reading some of the recent postings regarding the Edelbrock for WCFB swap, and now I am confused. One posted statement said to connect the vacuum advance to the full time vacuum port (which is the small vacuum port on he drivers side). Another posted statement said to connect the vacuum advance to the ported vacuum port (which is the small vacuum port on the passenger side) and yet another posted statement said that with the electric choke, no vacuum ports were to be used (if this is the case - where does the vacuum advance go)? Please help clear up my confusion, Maybe I am missing something. Also, I installed an Edelbrock 1403/500 cfm with electric choke, but I was told I could have used the 1406/600 cfm, what problems would the excessive cfm create.

Confused in Missouri

Studebaker Fever
60 Lark
51 Champion
Phil

[N8N]

with the electric choke, the u-loop in the manifold itself is what is not used.

Personally I am using the ported vacuum, and it seems to work OK, but I'm not 100% certain that that's absolutely the correct thing to do.

nate

--
55 Commander Starlight
62 Daytona hardtop

http://home.comcast.net/~njnagel

[Mike Van Veghten]

The 500 cfm carburetor is the one to use, stay with what you have. It's a volumetric effency thing. Actually a 450 is better for a 259. The 500 is more that fine. There is many free programs in the net to insert your engine figures and will spit out the numbers.
600 is good for over 300cu. in. and up going to 6000rpm.

As far as the ported - unported vacuum advance...."experiment"....
There was no such thing as "ported" vacuum in 1960. It's an outcome of the smog era. So stock, they were most all unported. There may have been some experimenting going then, but...
As I said...experiment. There really is no right or wrong. Add to that, NO vacuum. My 259 Lark currently runs great with no vacuum advance. They all will take a little tuneup difference. More or less initial spark lead.

"Ported vacuum" - this pulls vacuum as you are accelerating only and pulls no vacuum at cruise speeds, requires less initial timing.

"Non-ported vacuum" - This pulls vacuum at normal cruise speeds and drops vacuum when you accelerate, "can" require slightly higher initial timing.

"No vacuum", is a delicate balance of "enough" timing to properly serve cruise speeds and not be too high during acceleration (high load).

Have fun.

[60Lark]

Thanks for the help. I currently have the vacuum advance on the full time vacuum port and timeing is at 4 degree BFTDC as it calls for in my shop manual, I also have converted to a Pertronix breakerless ignition, which is night and day better than the old points. The engine was completely rebuilt this past winter. My only problem with the new carb is that I am having problems getting it to idle as smoothly as it did before the carb change, it runs out and accelerates far better but I am still playing with adjustments trying to get the idle a little better.

Thanks again

Studebaker Fever
60 Lark
51 Champion
Phil

[MarkC]

Prior to the late 60's, vacuum advance units on most engines were supplied ordinary manifold vacuum. Manifold vacuum varies with engine load and throttle opening. It's "high" at idle (when the throttle is closed) and normally high under low effort conditions (like cruising at 45mph in high gear on flat pavement). It's "low" under heavy acceleration (like when the throttle is suddenly floored) and heavy load conditions where engine speed is low and the throttle is (wide) open. With this in mind, engines using manifold vacuum will have maximum vacuum advance at idle (beneficial, since it requires less throttle at idle speed) and it will retard under heavy load (also beneficial, to reduce detonation). This really works quite well in concert with mechanical (or centrifugal) advance, which varies strictly by engine speed.

"Ported" vacuum came about with early (primitive) emission controls and it simply cuts off vacuum supplied to the advance unit at idle since the port is located above the throttle plates (which are closed or nearly closed at idle). On the up-side, less advance at idle reduces unburned hydrocarbons. On the down-side, less advance at idle requires slightly more throttle opening to maintain idle speed. Once the throttle is open, ported vacuum advance essentially acts the same as manifold vacuum advance.

As for what port to use on the carb itself, I mentioned in another post that you should test them to determine how they function, rather than trusting any instructions. It's simple enough. If there is no vacuum at idle, and it appears when the throttle opens, the port is "ported". If there is full manifold vacuum at idle with the throttle closed, it's a normal manifold vacuum port. The carb on my car is a 500cfm Weber version of the AFB, and I couldn't find a port (small diameter) on it that supplied manifold vacuum at idle. So, I put a "T" in the intake manifold where the power brake booster would normally connect to feed the vacuum advance unit, and I don't use any ports on the carb itself. My 259 runs great using manfold vacuum advance and I noticed a gain in milage when I started using it (since I could then turn down the idle speed screw on the carb).

Lastly, I have an electric choke and I still utilize the pre-heat loop in the manifold to supply heated air to it. This works great too as the choke opens quickly and functions fine.

Good luck.

MarkC

MarkC, 64 Y8
Working in Spokane, WA

[Sonny]

quote:Originally posted by Mike Van Veghten

The 500 cfm carburetor is the one to use, stay with what you have. It's a volumetric effency thing. Actually a 450 is better for a 259. The 500 is more that fine. There is many free programs in the net to insert your engine figures and will spit out the numbers.
600 is good for over 300cu. in. and up going to 6000rpm.

As far as the ported - unported vacuum advance...."experiment"....
There was no such thing as "ported" vacuum in 1960. It's an outcome of the smog era. So stock, they were most all unported. There may have been some experimenting going then, but...
As I said...experiment. There really is no right or wrong. Add to that, NO vacuum. My 259 Lark currently runs great with no vacuum advance. They all will take a little tuneup difference. More or less initial spark lead.

"Ported vacuum" - this pulls vacuum as you are accelerating only and pulls no vacuum at cruise speeds, requires less initial timing.

"Non-ported vacuum" - This pulls vacuum at normal cruise speeds and drops vacuum when you accelerate, "can" require slightly higher initial timing.

"No vacuum", is a delicate balance of "enough" timing to properly serve cruise speeds and not be too high during acceleration (high load).

Have fun.

Gotta agree with you on this one Mike, the 500 is more than adequate for either Stude V8 as long as it's normal driving. I much prefer the hand choke, (have had problems with a couple Edelbrock electric chokes, opening when they needed to be, a lot of tinkering to get 'em working right, and I don't like the fact that they close as soon as the 12 volts is off when you're making a short stop, like for fuel or milk, etc., makes for rough running on a restart).

The "terms" ported and un-ported were coined in the sixties to designate types of pollution switch vacuum circuitry. I have to say that nearly all older cars were what is now described as "ported", including our Studebakers. On the two barrel Stromberg, you can normally feel just the tiniest bit of vacuum at the vacuum advance connection on the carb. at normal curb idle., (that confuses the vacuum advance system for some), but remembering that Studebaker used a heavy spring in the vacuum advance, that little bit of vacuum at normal curb idle did nothing. According to the Stude shop manual, there are specific inches of vacuum and rpms listed, (can't remember what it they are right now for the non-Jet Thrust V8), that the vacuum advance starts to advance from idle, and a higher RPM that it should be at full advance when you accelerate, so I'd say that a fella could call that "ported".

I also agree that you should "experiment" with the timing. Once again, set the highest initial timing, at a point where the engine doesn't have detonation under load, (with the vacuum advance reconnected after you set the initial timing). Also, remembering that you can set the vacuum advance to "come in" or start to advance by adjusting the vacuum advance. Get a long Allen wrench, stick it in the vacuum connection on the vacuum advance and start tuning by turning it left and right. That may be your problem that your Lark is running better without the vacuum advance connected Mike, it just needs adjusting.

There really is a right and wrong when using the vacuum advance, it just takes some experimentation, as you suggested, especially if there's wear on the components that effect timing and carburetion.

I would describe "Non-ported vacuum" as.... "This pulls full engine vacuum at idle, (approx. 18 inches), and normal cruise speeds, completely negating the effect of the vacuum advance, as it's at full advance at all times, but retards timing as the engine drops vacuum when you accelerate, "probably will" require lower initial timing."


Sonny

http://RacingStudebakers.com

[60Lark]

That information helps a lot - Thanks

Studebaker Fever
60 Lark
51 Champion
Phil

[Sonny]

quote:Originally posted by 60Lark

Thanks for the help. I currently have the vacuum advance on the full time vacuum port and timeing is at 4 degree BFTDC as it calls for in my shop manual, I also have converted to a Pertronix breakerless ignition, which is night and day better than the old points. The engine was completely rebuilt this past winter. My only problem with the new carb is that I am having problems getting it to idle as smoothly as it did before the carb change, it runs out and accelerates far better but I am still playing with adjustments trying to get the idle a little better.

Thanks again

Studebaker Fever
60 Lark
51 Champion
Phil

Sounds like you may have a vacuum leak somewhere Phil. Also, you're using the wrong port for the vacuum advance. IF the vacuum advance diaphragm is good, and if you're using the full time vacuum connection, your curb idle rpm will be too high and you can't set the idle rpms low enough to set/tune the carb., (the mixture screws basically become less effective as the idle rpms go up and are ineffective at much over 800 rpms).

In fact, here's a test... At normal curb idle, using the full time vacuum port that you've already connected to the vacuum advance, pull the hose/connection off at the carb. or at the vacuum advance and you should hear a drop in engine idle rpms. If you do not hear/see that rpm drop, the vacuum advance diaphragm has a hole in it and must be replaced. What you actually have is a big vacuum leak and it's impossible to tune the carb.. In any event, the "ported" vacuum connection is the correct port to use on our cars.

What I would do is, (after you've determined that the vacuum advance is OK), set the initial timing to 8 degrees BTDC, (using the procedure as outlined in the service manual and using the ported vacuum connection as your vacuum source), drive the car, putting it under load, (accelerating rapidly, etc.), listening for detonation/pinging at 8 degrees initial timing setting. If you have detonation, reduce the initial timing to 6 degrees BTDC, check it again. If it's OK at 6 degrees, leave it there and enjoy the increased mileage and cooler operating temperature.


Sonny

http://RacingStudebakers.com