Something is real fishy about that.

Edelbrock used (1)1403 and (1) 1404, the difference being one of them had an electric choke, for their dual quad setups when they used Performer carbs.

1403 P jets .086" S jets .095" Rods .065" x .052" spring orange (5")
1404 P jets .086" S.jets .095" Rods .065" x .052" spring orange (5")

They used 1803 and 1804 for the AVS dual quad setup.

1803 P jets .086" S jets .077" Rods .065 x .057" spring orange (5")
1804 P jets .086" S jets .077" Rods .065" x .052" spring orange (5")

MIght need to measure things and see what you really have and compare it to the Edelbrock dual quad cals.

Stupid thought?? Can I just change the S jets to .077 and spring on 1403 to .057 (assuming mine is a 1403 & 1404} ?

Tried your "This Guide". Could defiently tell a difference, but still seems a little rich. Raining here, so I didn't test drive it yet. Probably needs more fine tuning. Patience may be my greatest weakness .

Remember most 2 four setups are progressive linkage so at one to one are way too rich unless running wide ipen.


The s jets are the secondary jets and unless you're rich at wot that's not the problem. If you are rich at wot changing the secondary jets will help. For each 4% leaner move you want decrease the whole by .003. It's listed on page 14 of the tuning chart. The primary jet is bigger because the metering rod goes inside the hole. The rods have two sizes on them they move up and down to increase or decrease fuel.

They first thing you have to do is find out what carb and what size jets and rods are in them now. Here https://static.summitracing.com/global/images/chartsguides/e/edl-1400_fm.pdf look up chart for the number carb you have and it will show what rods and jets to use. A rod change is quick and you'll know what direction to go.

If they are 500 performer changing rod to #6 .067 x .055 it will lean out cruise and power 4% #11 change only jet to .083 and use the factory rods will lean both out 8% and lastly #10 change jet to .083 and rod to .067 x .055 it will lean them out 12%.

On the setting up the two carbs before you put on linkage the backing out of the 2 idle screws to set the carbs the same I was taught after getting them set to set the idle to 2,000 by by turning each idle screw the same number of turns and put your hand over each airhorn to see how even the suction on the carbs are because the difference in the carbs,cylinders and the manifold.You'd be surprised how close you can get them with just a minor turn on idle screws. Poor man's mercury gauge.

Good luck

Second 70, I really appreciate you attempt to help, BUT it's way over my head. I basically am a simple basic person.
In your opinion, changing to progressive should be my first action, and it will reduce the "richness", but probably not enough?
Could not get your link to open for me. Thank You.

It might help a lot or not I don't know for sure.

Sorry that link doesn't work for you try this one.

https://edelbrock-instructions-v1.s3.amazonaws.com/edelbrock/carb-tuning-guide.pdf

If not just go to edelbrook web site click on 500 profomer and the click on tuning guide.

Maybe another member close to you might be able to help you out.

One thing to check is to make sure the metering rods are all the way down at idle, it they are bouncing or not fully depressed, it will throw off your A/F. It's easy to check, just loosen the caps and rotate them enough to see the rod- do one on each carb, all 4 to be through. Then start it up and see. If the springs are too stiff for the idle vacuum of your engine, you will need to replace them. If all 4 are good, then just move on from there. I'd suggest fresh plugs-or sandblast cleaning and re-gapping the old ones and giving it the old Italian tuneup and see how it goes. Remember timing needs to be set right first, then idle speed, then mixtures. If you've got vacuum leaks or the throttle shafts are worn or binding, it all needs to be fixed first. I'm not trying to talk down to you, so if it seems too basic, it's not an insult. I just don't know your background or anything about the car you are working on. If you've got an aggressive cam in it shoot for 1000/1200 rpm at idle, as long as it isn't dripping fuel from the venturis and the mixture screws are able to affect the engine speed. You've got the basic balance taken care of so after blowing the carbon out get the idle mixture set and go from there. It may be worth your time and money to get it on a chassis dyno to get it tuned. HTH, Steve

I have no idea what your mechanic friend is talking about. Carbs are fairly simple devices. They just use small holes to meter fuel and air. If your carbs are too rich then you make the fuel holes smaller and/or the air holes larger. You have idle, cruise, power and acceleration circuit adjustments on those carbs.

Idle should be easy to adjust since you just screw in the adjusters. Cruise and power adjustments require changes to the jets and/or the metering rods.

1:1 throttle adjustment should work okay with those carbs. Maybe not quite as nice as a good progressive setup but 1:1 isn't the reason you are rich.

If all of this is over your head (and obviously too complex for your mechanic friend) then find a local chassis dyno shop where the operator knows Edelbrock carbs. It will take a good Edelbrock guy about 2 hours to chassis dyno tune a dual quad setup and he'll probably charge you $300.

Thanks Steve. You can not get too simple for me, I appreciate the thought. I do a lot of "piddling", and get a great joy of being able to do as much myself as I can. Often as not, my work creates more issues than I solve, but I tackle most.
OK now, to be sure, I can check all 4 at the same time, or check all 4, one at a time, engine at idle?
I'm working on a 48 DeSoto, 1st Gen (1958) Chrysler Hemi, 2 4's. Auto tranny (A727TF), mild cam, small stall converter. Although I go to car shows, I always choose not to be judged. It's a driver, and I enjoy the people, the cars, and maybe couple of cold ones.
I just replaced plug wires (MSD 8.5mm,) (plugs (NKG) . Waiting for new coil (MSD Blaster2).
No moparts members near, very rural area, Chevy people up the ying yang.

I ain't a dual quad expert but I have one on the shelf (iron RB intake/2 4131 AFB's) so I am gonna learn also when the time comes but I cant help thinking that it ain't jetting, that it is one of these: psi/waterlogged float/float linkage hanging up/bad needle & seat/issue with metering springs/minute debris stuck on needle/seat. holler how it turns out.

Not stupid at all.

In fact it's pretty smart. I would verify what you have for a carb and if they are 1403/1404's I would mimic the Edelbrock calibrations as a starting point. One thing I have seen in my Edelbrocks is the floats tend to leak over time, gas gets in them and they sink causing a rich condition. If you pull the float hold it up by your ear, shake it and it rattles you have one of the holey floats.

You are welcome, It's really easy to check, the little cap(s) have a small flat blade screw holding them down. With the engine OFF, crack the screw loose, hold the cap down with a finger, the metering rod/spring will be pushing up on it. Then loosen the screw and rotate the cap just enough so you can see the metering rod, then tighten the screw to hold it down.Push the the metering rod down and let it spring back up, it should psuh down with little pressure and spring right back up. Do this for all 4 metering rods, that way you know none of them are bound up and the springs are't broken or bad. This should take a few minutes to do. Then hook up a vacuum gauge and start it up. Watch the metering rod assemblies, they should be bottomed out. You can push down gently with a screwdriver to verify that they are bottomed out. Again if they are, you are golden. If they are bouncing around, look at the vacuum gauge to see what springs you are going to need. If you don't have it I'd recommend the Carter/Edelbrock carburetors book #SA130 It's got lot's of pictures that are easier to process than a wall of text. Have fun

Skeptic wrote: "One thing to check is to make sure the metering rods are all the way down at idle, it they are bouncing or not fully depressed, it will throw off your A/F."

EXCELLENT suggestion. I had forgot about this. Will make your idle crazy rich if the rods are not seated at idle.

I didn't see this last night when I was typing out my wall of text, very good resource, I'd forgotten about it, Well Done!

Thanks MoParters. You are great, and I appreciate all the good info. Gives me some good suggestions, which I will use. If anything else pops into your minds, please share with me, and others who may be going thru the same issue.

Again, many Thanks.

You're welcome (I know you ain't referring to me!) All we ask is when the time comes to holler with what it ended up being.

Will do.

I am assuming this to be done with engine at aperating temp??

Reporting live from my garage in Southside Virginia...........Preformed your test, all checked OK. Engine off, could easily get them to bottom out, they would spring right back up, Check. Started engine, they bottomed out, and not bouncing, Check.
That was simple easy test, my Carbs passed. Anything else I should check? THANKS

Passed the test Skeptic asked me to preform. Don't know what's next, but will post all new delevopments.