Who has a fat cam 440 with a 750-800 cfm Edelbrock and an off-idle dead spot?

[74Rallye]

I certainly did until I put a Demon on it. This has always bothered me because Edelbrocks are great carbs and I've used many of them and the only problem I've ever had is the off idle dead spot with my 440. Big cam and low vacuum must make for the perfect storm for these carbs. I spent countless hours with the calibration kit trying to get more fuel in at low RPM.  I had this problem with a new 750 and a new 800. A 650 Edelbrock worked fine for drivability, but not so much for performance. The problem became unacceptable after I swapped in a 4sp. The only way the car would move was with a 4K RPM launch to get past the dead spot.
Then I saw this video.
   https://www.youtube.com/watch?v=aX2v-du5ias&list=WL&index=55
I will try this mod in a couple of months as I've got snow and salt everywhere now. Check out the video and lets hear what you think. I really think this is the answer I've been looking for.

[gsmopar]

If you're not doing a restore, there are a lot better options than the old AVS carb design.  I haven't touched one since the 90's.   

[74Rallye]

I have a 800 eddy that I bought new and put less than 500 miles on it. The Demon is incredible for great drivability. The eddy is better at WOT, but has zero drivability with it's dead spot. It's not useable with a 4sp. I want the satisfaction of making it work.

[cbrestorations]

I don't know much about Edelbrock's as their not even worth the time to tinker with but what ur dealing with sounds like a transition slot issue with a holley. If you have ur throttle blade open too much so it will idle, you have skipped the transition slot circuit that meters that off idle to cruise load range. Drill a bleed hole in the butterfly's next to the slot (start at 1/16) and then use rear throttle blades to fine tune idle rpm. You want about .040 showing on the transition slot with primary blades

[hemi-hampton]

I don't know much about Edelbrock's as their not even worth the time to tinker with but what ur dealing with sounds like a transition slot issue with a holley. If you have ur throttle blade open too much so it will idle, you have skipped the transition slot circuit that meters that off idle to cruise load range. Drill a bleed hole in the butterfly's next to the slot (start at 1/16) and then use rear throttle blades to fine tune idle rpm. You want about .040 showing on the transition slot with primary blades

I read about that Trick in a Magazine. I had a 800 Edelbrock on my Car & had no Problems. The Cam was a older 1970's Racer Brown with somewhere around 540 lift & 292 Duration (advertised) Not super huge but far from stock & a 3,800 rpm Stall Converter & Cheetah Manual Reverse Valve Body. And a 4:56 rear later changed to a 3:91 for more Drivability. LEON.

[BSB67]

Yes, open the IFR.  This is often the fix, Edelbrock or Holley

[white]

Installed an Edelbrock AVS2 and all my stumbling off idle went away. Make sure you only have 5psi to the carb.

[MGBRingo]

AVS2 solved my issues also.  The best running carb I have ever used. 

[RallyeMike]

I always dump my clutch at 4000+ so I have not noticed 

[KurtfromLaQuinta]

Yes, open the IFR.  This is often the fix, Edelbrock or Holley

Indeed.
On my Six Pack just a couple of sizes up on the Idle Fuel Restrictors made a huge difference in driveablity.
BUT... it's a mod you must do yourself unless you have a late model "something" carb. I'm talking drilling and tapping to put jets in their perspective locations. It not that hard. And the benefits make it more than worthwhile.
IF you have a Holley... here's an article I transcribed over where I hang out at Ramcharger Central...

https://ramchargercentral.com/technical-discussion/the-best-way-to-tune-a-holley-carburetor!/

By far the best article I've ever found on tuning a Holley.

[375instroke]

Look into drilling a hole in the throttle plates.

[Rolling_Thunder]

Usually the stumble off idle is due to the vac signal interruption - I had it on my old 383 with a 292 purple shaft cam in it --- was running a 750cfm Edelbrock as well...   ended up going to a larger accelerator pump nozzle (0.043") and it cleared it up quite nicely