Edelbrock 600cfm...Learning how to set it

[zerfetzen]

Hi all,
I bought a new Edelbrock 600cfm 4-barrel carb with manual choke for my newly rebuilt 318.  Question: how do I set it?  It is stock...no fancy jets or anything.  I'm new to this and would like to conquer an Edelbrock before stepping up to a Holley in the future.

The vaccuum advance is plugged into the right inlet.  It looks pretty simple...on the right is a screw for idle speed, and in front are 2 screws, I think for adjusting air/fuel mixture.

Person #1's advice:
One guy showed me how he would set it, which was to screw the right mixture screw in (while warmed up and running) until the idle starts to drop, then back it off by one turn.  Then, do the same thing with the left mixture screw.  At this point, they should be set the same (I guess I want that) and lean.  If I back them out, then I'm adjusting to a richer mixture.  He also said that a 600cfm is way too much carb for a 318, and I should run it lean.

Person #2's advice:
Another guy said that using a vaccuum guage is crucial, and I should set it to about 18.  So I bought a vaccuum guage and haven't a clue how to use it, or if his guess was right.  I'm guessing I'd disconnect the distributor vaccuum advance and plug it in there?

I've tinkered with it a little, but am ready to hear from the pro's...how would you do it?  Thanks.

[dimples]

Well, you can plug the vacuum guage into the manifold vacuum, and simply adjust the idle mixture to get max vacuum.
OR

I run each srew in, untill I hear a drop. (too lean)
Then, back them out, untill I hear a drop again. (too rich)
And then just simply find the happy place inbetween. It may take a few tries, but you will get the hang of it.
A 600 CFM edelbrock, is not too big, for a 318, and is actually too rich for most mild 318's on the main side, and too lean on the secondary side. Timing, manifold, cam, and everything else comes into play too, though.
Once you master the tuning of the edelbrock, and get your springs, needles, and jets were they need to be, you probably wont need a holley. (IMO)
Edelbrock has a nice tuning book, that tells you all about the carbs they build.

[Mopar73340]

  I have one of those carbs and although some people don't like them, once you get it tuned you won't have to mess with it again. Also Facing the front of the carb, the vac advance should be on the left.

[zerfetzen]

Thanks a lot dimples, I knew Edelbrock's were simpler than Holley's, but I never knew they really were THAT simple.  Cool.

Quick question Mopar73340 (nice number in the name by the way), so the vaccuum advance should be on the passenger side (front) of the carb?  I could've sworn (and probably did)...

[Mopar73340]

Quick question Mopar73340 (nice number in the name by the way), so the vaccuum advance should be on the passenger side (front) of the carb?  I could've sworn (and probably did)...
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Thanks, The vac advance hose is connected to the port on the pass side front of my 600. It's easy to check though. The correct port will NOT have vac at idle.

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I looked in the manual, and here's my confusion:

Left (passenger) port = timing port for emissions controlled vehicles
Right port = manifold port for non-emissions controlled vehicles

On the one hand, since it goes to the distributor, I'd want the timing port.  On the other, my Cuda doesn't have any emissions stuff on it.  Just double-checking...

[basement]

I too have the Edelbrock and am realitively happy with it. Someone correct me if I'm wrong but aren't the two mixture screws in the front only for idle to partial throttle? With that being said how are the remaining throttle positions tweaked?

[Mopar73340]

I looked in the manual, and here's my confusion:

Left (passenger) port = timing port for emissions controlled vehicles
Right port = manifold port for non-emissions controlled vehicles

If you use the port on the right for the vac to the dist, you will have full vac advance at idle as that port has manifold vac all the time.

Basement, As to the rest of the settings off idle, they are controlled by the jets and metering rods, Did you get a owners manual with your carb? If so they are explained in there. If not, you can download one at Edelbrocks website.

[zerfetzen]

Thanks about the port, you can see how that's completely unclear to a newbie.  Cheers.

[dimples]

I too have the Edelbrock and am realitively happy with it. Someone correct me if I'm wrong but aren't the two mixture screws in the front only for idle to partial throttle? With that being said how are the remaining throttle positions tweaked?

OK, quickie Edelbrock 101.
The idle adustment, is adjusted by the screws on the front, you are correct.
After the throttle is opened, the mixture is controlled by vacuum. under the little covers, on the top of the carb. (the little tear shaped ones held on by one screw) is a piston, a spring, and a needle. At the end of the needle, is a jet. When the throttle is opened, the engine loses vacuum, and the piston, attached to the needle, rise. (this is adjusted by the spring tension) When they rise, they pull the needle out of the jet, wich feeds fuel into the engine. Once very low vacuum is reached, the piston rises all of the way out of the jet, and just the jet is metering fuel. (this is achieved, if the springs are the right tension, and the carb is the right CFm for the motors intake, right before the secondaries open) There are different needles and springs to adjust this process, and it can be very tricky, for ones just starting out on carbs, BUT, once you have master'd the mains on a edelbrock, nothing on a carb wil ever scare you again! LOL.
(This also is why people hate tuning Edlebrocks)
The secondaries, are really easy to tune, and are meter'd simply by the secondary jet, and the vacuum operated door. The door meters the air going thrue the secondary's, (creating a certain amount of vacuum) and feeds fuel simply by a siphon effect.
Basically, these types of carbs, meter fuel by monitoring the engines demand for fuel, through vacuum, and not from throttle position. (good for gas mileage!)
I would suggest getting a Edlebrock tuning book, and, the tuning kit for your carb, I think the kit # for yours is 1479.......(check to make sure, I just pulled it out of my head, LOL)
OK, I hope I made sense, and apoligize if I lost you.

[zerfetzen]

Really good intro tutorial, and I'll definitely get books, I'm into learning.  One quick question to get me by in the meantime:

Soon I'll be switching my ignition to MSD.  The MSD distributor does not have a vaccuum advance running to the carburetor.  Do I plug up both front ports?  Do I run a hose from the right (manifold) port down to the intake manifold?  Thanks.

[dimples]

Just pop a couple plugs on them.