I *think* there are some generalizations we can make about the 1406 that apply to any engine we could describe as "big block" and "pre-emission control".
I assume you have a reasonably close to stock cam, otherwise you wouldn’t be running a 1406 anyway. So I won’t throw in any “if you have a really big cam” alternate instructions. I also assume you have a relatively stock torque converter. It is a lot more of a challenge to solve a stumble or hesitation with a low-stall (stock) converter than with a “loose” high-stall. People with high-stall converters usually don’t complain about off-the-line bog, they complain about lousy gas mileage and broken transmission or driveline parts.
First, the 1406 is lean, on purpose, on the primary side. It has a sister carburetor - the 1405 manual choke - that is jetted richer for performance. Which is to say the 1405 would not pass an emission test, nor would it get gas mileage as good as the 1406. If you have a non-catalytic converter, dual exhaust big-block, the 1406 is a bit lean at sea level (but about right if you live in Denver.)
Second - the primary side of an Edelbrock has jets (like a Holley) and Metering Rods (like a quadrajet, various Carters including the AVS, AFB, and Thermoquad, etc.) The metering rod has steps where it narrows. When you have high manifold vacuum, the "rods are down" and the thicker part is in the jet, restricting the fuel flow through the jet, thus making for a leaner cruise mixture. When you step on it, say going up a hill, the vacuum drops and the "rods are up" meaning the narrow part is in the jet, thus making for a richer mixture. You don't have to completely floor the throttle to have low manifold vacuum, especially at lower RPM's.
I told you that so I could explain this part: the 1406 has metering rod springs that are set at 4" hg. That's about like having a 4" power valve in a Holley. What that means is the “rods are down” until you approach only 4” of vacuum, then they go up and richen the mixture. You may notice a bit of a “lean hole” around 5” of vacuum with a 1406. That is because engines under a load like a richer mixture than engines at cruise. All the other Edelbrock carbs have 5” metering rod springs. But since the 1406 is the “mileage/emissions” carb, they sacrificed some drivability by using a 4” spring. Note the “inch” of the “spring” has only to do with the manifold vacuum at which the rods go up (or down). It has nothing to do with the length of the spring. Long story short – toss the 4” and use the 5”.
Third – the pump shot is not optimized for your engine. If you had an 84 Chevy with a 305, a catalytic converter, and a single exhaust, it would be great. But not on a 383 or 440. There is only one accelerator pump on an Edelbrock, but there are two ways to adjust it.
Keep in mind the accelerator pump plunger has an internal spring, so you can only get it to move so much fuel in a certain amount of time, given the restriction of the squirter nozzle. There is no alternate or high performance pump plunger, so we can't change that. There is only one size of pump, we can't go get a bigger one the way we can change a Holley 35cc to a 50cc.
The first accelerator pump adjustment is changing the hole on the arm that the rod goes through when moving the pump. For some engines, lengthening the pump shot by putting the rod in the top hole (the hole closest to the carb body) is enough to solve a stumble. However, the pump plunger inside the carb is on a spring, and will only push so much gas out so fast, so this does have limits.
The second accelerator pump adjustment is changing the squirter nozzle. The 1406 comes with a 0.028 sized squirter, which is pretty small. The kit #1475 comes with 0.024, 0.033, and 0.043 squirters. Going to a bigger squirter allows the accelerator pump to get the fuel shot out quicker. For the most part, it seems (from what I can gather) guys who go to a 0.043 pump say it solves any bog or stumble. In my case, I had to do both the 0.043 squirter and had to use the top hole.
I really don’t think it is possible to have too much pump shot with an Edelbrock 1406 on any pre-emission big-block Mopar. Seriously. I don’t think the design allows for it. The accelerator pump is not that big. The accelerator pump is barely adequate and that is all.
Fourth – 10% ethanol leans the mixture by 4%. That’s a lot when you are tuning, and even more when you start off with a carb that is lean to begin with. If you can avoid ethanol, do so.
My best guess? If you haven’t already, set the timing per Mopar Performance guidelines, use the 0.043 squirter, set the pump in the top hole, and use the “orange” 5” spring. That should do it, and if you want to fine tune with richer rods/jets go ahead. The 1406 seems to like being about 8% richer on the primary side.
Joined: Thu Mar 01 2007, 09:30PM
Location: Houston
Posts: 1735
The best fix is to modify the Edelbrock by converting it to a diaphragm accelerator pump and revising the jet layout to eliminate the metering rods. Then, rework the float bowls to a side hung design and position the jets such that they don't sit at the lowest point in the float bowl. Remove the big air restriction in the back two barrels and add an accelerator pump there, too. Give each float bowl its own needle and seat, and its own fuel line. Last step is to carefully use a Dremel tool to grind the letters HOLLEY into the side. When you do all those mods, you'll have a carb that runs well.
Joined: Wed Nov 17 2010, 03:28PM
Location: florida
Posts: 1311
Just a note . someone mentioned adding an elec choke to a manual carb , some newer eddy manual choke carbs cannot be switched to an elec choke. I gotta say that when it comes to carbs your either an eddy or a holley guy. I like both but i like the ease of tunability that doesnt require an MIT degree and carbs that dont leak,so i run an eddy.if i was racing for time i would use a holley for sure.
Joined: Sun Jul 18 2010, 11:11PM
Location: DFW
Posts: 811
gregcon wrote ... The best fix is to modify the Edelbrock by converting it to a diaphragm accelerator pump and revising the jet layout to eliminate the metering rods. Then, rework the float bowls to a side hung design and position the jets such that they don't sit at the lowest point in the float bowl. Remove the big air restriction in the back two barrels and add an accelerator pump there, too. Give each float bowl its own needle and seat, and its own fuel line. Last step is to carefully use a Dremel tool to grind the letters HOLLEY into the side. When you do all those mods, you'll have a carb that runs well.
This sounds like a person who has no clue when it comes to tuning AFBs. I certainly don't want to go backwards when it comes to carburetors so I'll stick with the AFB.
Well, this is turning into an amusing thread! I think much of this current discussion started on another post, and on that thread my initial recommendation was the 1406. But frankly I think it about a coin toss, so when asked for recommendation on Holley I suggested the 670 over the 570 based on personal experience.
I'm on multiple sides of this Holley vs. Edelbrock thing. Planning to go FI at some point, but saw enough guys complain about the bog in a 1406, thought I could figure out a way to make it go away as a challenge, really.
I think most bog issues are timing and distributor related anyway. No carb will work well if the base timing, total timing and timing curve are off. True especially with small-block Mopars with parts store replacement electronic distributors - the timing curve in the late 70's to mid-80's small block distributors is way off of ideal for performance and throttle response.
With either a Holley or an Edelbrock it takes some tuning to get the bog out in a heavy car with a 2.76 gear and a low-stall converter. In one car with a 770 Holley I found that adding drag radials to it (so that it wouldn't just spin the tires) but then made it stick created a bog, too. Fixed that one with a higher stall converter.
Holleys tend to be fuel-swilling pigs when people cam the engine up but don't change the power valve. If you want a Holley to run right, get the power valve right first, then move on to jets, squirters, etc. Which is why I recommended a Holley 670 over a 570 in another post - it comes out-of-the-box with the right power valve for a stock 400.
The same tune setting that might bog like crazy in an Imperial or a T&C Wagon will not bog in a 440 Dart with 4:10 gears and a 3500 stall converter.
The benefit of the Holley is you have more control and flexibility with accelerator pump shot (cc size, pump cam size/shape), secondary opening rate, and some versions have 4-corner idle. Not to mention the response of the double-pumper. For a car with a longer duration cam, (a longer duration than a 383/440 TNT/Magnum) I think the Holley is a much better choice due to its tune ability.
For an otherwise stock C-body big-block Mopar, I think they are roughly at parity. Maybe a slight edge to Edelbrock for economy and stock-like behavior (starting, warm-up, etc.) and maybe a slight edge to Holley for full-throttle performance. Maybe a tip to the Edelbrock on a "base" engine and a tip to the Holley on a "TNT/Magnum." But even then, I can probably tune the Edelbrock of my choice to out-power most Holleys on any given day, and I can probably tune the Holley of my choice to give better economy than most Edelbrocks on any given day.
Mopar engineers couldn't decide either. They used both Carter (now like Edelbrock) and Holley back & forth until the ThermoQuad replaced them all.
In terms of design, the Thermoquad was the best. Unfortunately, in terms of materials and workmanship, and ability to work on it or get parts for it, it just became impractical once to got too old. The phenolic base, advanced for the 70's, warped and cracked. It wasn't designed to be easily assembled or disassembled, tricky adjustments, etc.
I thought about trying the new "Street Demon 625" with the "goggle valve." It seems to combine the best of the TQ and the AFB. But it is only a 625, and I didn't think it would be worth it from a performance standpoint to change if the 1406 ran fine (which it does now.) That, and I had a Demon 850 some years back. I thought their build quality was poor and while the Demon was fabulous at full throttle, it didn't do anything else well at all. So I'm not sure how badly I want to rush out and buy another new product from Demon just to learn those lessons over again.
However, if there is another drydocker out there that wants to "take one for the team" and be the first to try the new Street Demon 625, I'd sure be interested to hear what they had to say about it once they tried it!
In the mean time, I'm saving up for fuel injection..........
I found the 1406 was set to lean for even my ford 302. I had to jet it up the same as the 1405. I run a 1406 & 1405 on my fury. Both have been set to run richer. I have never had any flat spot, but that could be because both carbs are squirting. This is good info though. When I ran an eddy 750. Every thing worked fine as well. Way better than the new holley 3310 I tried. I my self would go with a 750 as to a 600 for a big block. I think you would have less issues to deal with.
Joined: Sat Jun 16 2007, 01:18AM
Location: Grand Rapids, MI
Posts: 839
I thought my Edelbrock ran great on my 383 and 413 @ the time I had it...small stumble when the secondaries came in that I could never tune out once they had some cam in the motor, but I replaced it with a Holley and will honestly say I will never run an Edelbrock carb again...
I'm bored, and so am getting ready to do a little intake manifold/carb swap on my mild 383 with a never rebuilt bottom end and new big valve 346 heads, Comp XE268 cam. She never gets wound up tighter than 5,000 rpm because I don't trust the old bearings even though it holds a steady 80 psi oil pressure.
Right now it has a Performer RPM intake with an Eddy 1407 (750 cfm) leaned out as much as possible with the Edddy tuning kit (.104 primary/.100 secondary/ .075x.052 rods) but it is still too rich for the high altitude here - 5500 ft at home and even higher where I like to drive the old beasty-- up in the mountains of northern New Mexico, where the altitude varies from 6,000 to 10,000 ft.
I want a bit more low end grunt, and I just happen to have a Mopar M-1 Dual Plane intake and stock Eddy 1405 (600cfm) carb lying around, so I'm going to swap them out this weekend and see what difference it will make. I just put got done tinkering with the 1405 and put in bigger accelerator pump squirters (.035 vs. the stock .028) and some .068 x .042 rods in the .100 primary jets, and left the .095 secondary jets alone.
NOW FOR MY QUESTION: which set of step-up springs should I use? I've got the orange 5'' set in the 750 cfm carb now, which turned out to be way too strong when I went up to the top of Sandia Peak Saturday-once we went past 8500 feet or so, the rods were pretty much all the way up and it was dumping fuel like crazy: exhaust started turning black at the 10.700 ft top, and the raw fuel stink was overpowering. So obviously it needs a WEAKER spring so that the vacuum can hold the rods down in the lean position, but is that the yellow 4" or the silver or purple 7'' or 8" ?
Joined: Thu May 01 2008, 11:15AM
Location: Chicago,IL
Posts: 2868
I let my MAP sensor figure it out
It will be interesting to see what you think of the combo. As you already know, those heads are kind of mismatched to everything else on the engine, and now you're going to make them more mismatched by putting a smaller intake and carb on it.
Oh yea...HI DANA! 
Tony P.
