Technical Another Edelbrock Carb Question

Hey folks!
My 1406 Edelbrock carb on a basically stock SBC idles great cold or warm. But bogs down under a load until I let off the gas pedal. So I was wondering what a good way to tell if it's getting too little or too much fuel? It has 6 lbs of fuel pressure. I tell ya, I'm just about to the point of strapping my phone to the carb and filming it while driving-ha!
Unfortunately I don't know the history of the carb, but I've disassembled it 3 times now to clean it out, inspect, and check float condition and level. Each time I've found nothing that was a culprit. And the plugs, wires, cap, HEI are all tested and squared away.
Did a thorough thread research but just wondering at this point if there are any obvious signs I'm missing.
Thanks a million!

 

What jets and Metering Rods do you have in it?

 

Dunno if its troubleshoot or tuning time. The fuel pressure is on the high side for one of them, easy to tell by looking into the secondaries there are wells on either side of the booster/venturii, these wells is where the counter weights for the secondary air gate reside, look into the bottom of those wells and if there is blackish goo then the fuel pressure is too great and raw fuel is running into the engine, it'll also dribble into those wells.
If the fuel pressure is ok then its a tuning thing, look up the 1406 in the manual that came with the carb. It'll have a handy chart with the stock tuneup in the center. It sounds like its lean under power (like when pulling into a passing lane) then you'd want to refer to the chart and do what it say, quite a few changes are done with metering rod, some will need both metering rod and jet change. There is also another chart to help you pick the right metering spring depending on the vacuum and weight of the car.
It really is a good book, if you don't have it PM me and I'll email you the right pages you'll need.
First thing I'd check is fuel pressure.

 

Yah I'm not seeing or smelling any excessive gas anywhere in or on the carb. So the rods and springs can make a big difference huh? I'm going to look for that manual!

 

6 lbs. is high and reading the instructions is important.

 

Reading the manual as we speak! Wow, the rods work in opposite direction of what I thought!
Question: Can I loosen the screws on the little covers over the rod/piston area and watch their operation while in park to see if they move?

 

Yes.

 

careful,there are springs under there. They will go flying.

 

Ok, so loosen screws but don't turn cover all the way open-thanks!

 

I live at a similar altitude as you. My Carb Tuneup on my SBC 350. Primary Jet .098. Metering Rod 70x37 # 1449. Springs are orange

 

The fuel pressure as everyone stated is extremely important. A good fuel filter is critical. And read the tuning manual, it's got lots of good info in there. Write down where you start, and keep track of what changes you make. You'll be happy you did.

 

Play with the three hole positions on the accelerator pump rod linkage. See if one makes it happier than the others. Free and easy to try without disassembly.

 

Thanks guys, can't wait to try these things tomorrow!

 

Actually 6 lbs of fuel pressure is almost perfect for an Edelbrock carb they are designed to work best at 6 1/2 lbs as per the tune up manual from Edelbrock with a do not exceed pressure of 7 lbs. Since you have been inside the carb a few times I would check the Jets and Metering rods first thing. The manual is a very good thing to have as well. These are pretty simple carbs you will figure it out.

 

You may want to watch this video:

 

Jeff, Very good video thanks for that. I like the Edelbrock carbs a lot. Mainly because they are simple enough for this old country boy to work on and fix. I also like the Holley but have never had any luck fixing one when it goes bad, guess I am just not smart enough for those critters. I have always tuned my Edelbrock's strictly by the manual and have never had any problems, as a matter of fact I think they are really easy to tune. I have three Edelbrocks now, one on my Model A and two in a 2x4 setup on my OT pickup. I run Edelbrocks recommended 6 1/2 lb pressure in all three and never had a problem.

I found that video that to be interesting, looks like everyone is not as lucky as I have been.

 

Nope you cannot tell a thing about your problem while parked. Your problem is under load.

If it bogs it is not getting enough air. Do not think of your carb as a fuel meter think of it as an air meter and you will have better luck tuning it.

 

I run 5 lbs with no problems, some say 6+ is too much. Do a google search and see the amount of back and forth on this subject.


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^^^^^ I run 5 lbs too on all the ones I have-holley regulator--no problems

 

I run 5 - 5.5 fuel pressure as per the manual, normally you can feel a surge at given rpm's that indicates rich or lean condition. Once those are corrected the whole carb should be close.

 

Call Edelbrock's tech line, I did, they were a big help and help diagnose my issue. They sent me needles and springs free of charge. It fixed the problem. Give them a try.

 

Well since I work 3rd shift, I have a very small window of time to do anything during the week . And today's window was a dentist appointment - bummer!
So tomorrow it is! Thanks guys.

 

I've got a 1406 on my 58/350. I've tried two different fuel regulator's, and both of them ended up leaking. The last one was a Holley. I'm now running w/o one.

 

Well I had 5 min today to see if the rods were moving up and down when reving the motor in park and they do. So I'll save up and get the tuning kit. Just wish I knew if it was running rich or lean!

 

Out of the box, 1406's are set to run lean.

 

Almost wonder if this type of intake manifold simply needs more fuel than out of the box carburetor.

 

What are the specs on your engine and combination?


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Lean carb plus and air gap intake?

 

Single plane manifolds don't really start to work until 2500 RPM or higher. In my opinion,not very good for street use. The manifold therefore,could be part of you problem. Dual Plane manifolds work from idle

 

Kinda wondering about that. I know very little to nothing about the history of this motor.
Never used this manifold before on ANY of my cars. Online description of this particular intake recommends 650 - 800 cfm carbs. A 1406 carb being a 600 cfm, maybe I am starting out against a stacked deck?