edlebrock stumble

[Russtoy]

I am looking for a solution to my problem. I have 2 edlebrock 1406 carbs, one on a 383 mopar and the other on a 400 Pontiac. Both stumble right off idle, easy push on pedal, coughs hard when you hammer it. I have tried big, medium, and small squirt. changed timing cleaned the carbs way to many times. Any good carb guys here have an answer? I hope so. I am at a loss, and I don't want to buy a holley/ sieve, every holly I have had in the past leaks every spring when you fire it up. Thanks Russtoy

 

[mopar 3 B]

What is the vacuum reading at idle and is timing advancing just off idle?

 

[jimt1971rr]

Have you tried changing the jet rod springs? I have a kit, someplace, that came with 5 or 6 different tensions of springs to adjust how quickly the jet rods retracted. I saw that Edelbrock also sells an entire kit including rods and jets.

 

[miller]

Might also check the accellerator (can't spell this morning) pump(s) on both carbs.
Could be worn, or adjusted wrong. Also seen the bottom of the pots loaded with corrosion.

 

[junkpile]

edelbrock carb issue

Might also check the accellerator (can't spell this morning) pump(s) on both carbs.
Could be worn, or adjusted wrong. Also seen the bottom of the pots loaded with corrosion.

I had the same issue with my Eddy 750 one of the fuel bowl floats was too low. re adjust the float levels per spec (i believe it was 3/8" space whey you turn the top carb plate upside down) this solved my stumble off idle. I had one other issue with stumble at WOT (wide open throttle) and it was a metering rod issue along with increasing the accelerator pump nozzles. This is on a 440 .030 over 484/284 cam.

Hope it helps.

 

[mrsnicks]

My 1st check would be the accelerator pumps as well.

 

[Moparsmitty]

Souds like it's lean off idle. Try a size or two smaller metering rods (easy to change) and richen up the idle screws a little and see if that makes any difference.

 

[Hemirunner]

First, make sure the needles are down at idle and are coming up when throttled.

 

[Meep-Meep]

How much initial timing and is the advance curve working properly? Are you running a hot cam and low compression? What is the cylinder cranking PSI?

Verify floats are set to 7/16" at the middle of the float with gasket in place. Float drop should be 1" I believe but verify. Fuel pressure should be 5.5 to a max of 7 PSI. Verify you have the factory default jets and rods. Squared at .095" and a .073" x .047" rod (I think).

 

[Banzaiii67]

I had A Lot of tuning issues with a Edelbrock 1806 AVS

Here's everything I tried..

-rebuilt and gasketed the carb, cleaned every orifice and confirmed no obstructions in any air bleeds
-set the floats exactly to spec.
-put on the edelbrock heat insulator gasket
-increased timing-- 18 initial/34 Total
-ran vacuum advance off the manifold vacuum line and ported-- no change
-100% sure I didnt't have any vacuum leaks
-metering rods suck down orange springs and pop up without trouble
-tighten/loosen the secondary air door

What solved the off-idle stumble for me... Edelbrock Part # 1470, putting the Accelerator pump arm on the lowest pump shot setting ( less fuel) and running non-ethanol fuel. The 1470 accelerator pump spring is very tight wound and it makes the pump shot very responsive.

Edelbrock also do not like lots of overlap, or anything larger than a stock cam. It will require permanent modification to the idle circuit.

Regardless, the edelbrock I had on my car ran pretty well once i got rid of the stumble, the small venturis pull really well down low.. I just couldn't get the throttle blade closed so my A/F Ratio was terrible. Went to a Quick Fuel SS 680VS, and the thing ran great out of the box and haven't even touch the 4 corner idle, power valve or the bleeds.

 

[dvw]

I had A Lot of tuning issues with a Edelbrock 1806 AVS

Here's everything I tried..

-rebuilt and gasketed the carb, cleaned every orifice and confirmed no obstructions in any air bleeds
-set the floats exactly to spec.
-put on the edelbrock heat insulator gasket
-increased timing-- 18 initial/34 Total
-ran vacuum advance off the manifold vacuum line and ported-- no change
-100% sure I didnt't have any vacuum leaks
-metering rods suck down orange springs and pop up without trouble
-tighten/loosen the secondary air door

What solved the off-idle stumble for me... Edelbrock Part # 1470, putting the Accelerator pump arm on the lowest pump shot setting ( less fuel) and running non-ethanol fuel. The 1470 accelerator pump spring is very tight wound and it makes the pump shot very responsive.

Edelbrock also do not like lots of overlap, or anything larger than a stock cam. It will require permanent modification to the idle circuit.

Regardless, the edelbrock I had on my car ran pretty well once i got rid of the stumble, the small venturis pull really well down low.. I just couldn't get the throttle blade closed so my A/F Ratio was terrible. Went to a Quick Fuel SS 680VS, and the thing ran great out of the box and haven't even touch the 4 corner idle, power valve or the bleeds.

That's strange. My cam has 285/292@,050" on 112LCA, plenty of overlap, idles at 1000 rpm. The idle circuits are 100% stock. Easiest 1st step is to move the accelerator pump rod to the hole nearest the air horn.
Doug

 

[Banzaiii67]

That's strange. My cam has 285/292@,050" on 112LCA, plenty of overlap, idles at 1000 rpm. The idle circuits are 100% stock. Easiest 1st step is to move the accelerator pump rod to the hole nearest the air horn.
Doug

Maybe it's just me, i tried just about everything except for drilling the throttle plates, Icr or the idle tube. Nothing worked to get the throttle blades back down into transfer slots..

 

[coloradodave]

I'm with Doug on this one. I run 2 600 Edelbrocks on a crossram with a hot cam and stock idle system. Idles at 950 rpm and excellent throttle response...

 

[Russtoy]

Thanks for all the responses, I think I may have solved the problem, I raised the floats a little bit and the stumble almost disappeared. Much better, I will raise them a little bit more this week, I found a Carter tuning manual on line, and it is very informative, it describe what everything does and how everything works. Thanks for the help.

 

[Tempest 455]

I have two E 750's on a tunnel ram on a nostalgia motor w/ VERY crisp response. They needed many small changes, however. If you still need some data, I can post in the morning.