Some of us with 440s have experienced the off idle dead spot with Edelbrock 750s and 800s and it's related to particular engine builds, not a random defect in the carb as I haven't heard of this problem affecting stock 440s. I came across this video and I'm going to try this mod after the weather washes away the salt on the roads.
https://www.youtube.com/watch?v=aX2v-du5ias&list=WL&index=55
Has anyone tried this before?

That mod was the fix for the same problem with the factory AVS. Most drivability techs learned it in the sixties.

It looks like I'm going in the right direction then. Thanks.

^^^ thank you

That is a very good video for someone that insists on running one of those for what ever reason. It would have been better for all those that do not have a full set of tiny drill bits to mention what size the orifice started out at and what size it ended up at. .009" bigger is not the best way he could have communicated his changes.

With all the information and parts out there for the Holley platform carbs, I have always been surprised at the lack of CarterBrock parts and this kind of deeper tuning info given how many are out there.

But one look at the tuning charts for the metering rods and jets should still cause most guys to look for a carb elsewhere. I'll say again, the CarterBrocks are not necessarily bad carbs, it's just that there are much better choices out there today. Heck, in the Engine Masters recent cheap carb shoot-out, the CarterBrock came in last place. Even the Summit carb beat it.

Since the problem seems to exist throughout the AFB, AVS and Edelbrock series, the tube orifice size varies with the booster. We always increased the orifice two drill sizes at a time without paying any attention to the actual drill size.

all they're doing is richening up the idle jet. the idle jet is the small tube in the primary cluster. i do this a bunch and is a major help on factory avs's. in short go to .035" on the 600cfm carbs and somewhere between .037"-.040" on the 750's and 800's. i never use large squirters on anything i drive; they don't work. i do use the tan colored accelerator pumps exclusively. also look for casting flash in the groove that feeds the pump reservoir. simple stuff.

i'm going to add something else. i've found dealing with the 800avs (not the avs2) that taking fuel out does help them drive better off idle. they have a .040" idle jet and don't go bigger. i've reduced main metering jet area and used small squirters to improve tip-in.

74Rallye - is your car out of CA? I looked at one from CA. back around 1984 - looked the same as the car in your avator. It was parked under a car port in Phoenix, AZ. An amazing all original paint car in super condition - 440 automatic. I left a note on it to ask if it was for sale, but never heard from the owner.

Sunroof, My car came from Danville VA and rested in a junkyard in Evington VA before I got it.

That works for you. You must have a full set of tiny drill bits to choose from. But not everybody does.

A post or two later, it is noted that the drill range is " .035" on the 600cfm carbs and somewhere between .037"-.040" on the 750's and 800's." That is more very good info for those that don't want to buy a full set of drill bits to find that one or two that they will need to fix their CarterBrock's problem.

You have a vintage car, and you do not want to buy basic tools? A small index bit set is about $10. You are only drilling alum or brass. If you take your own carb apart to clean and rebuild you would want that set to clean out the bleeds and jets, even if they were sized correct.

Obviously, you misunderstand.

I have worked on CarterBrocks before so I have plenty of drill bits. I was just thinking of the poor guy that buys one of these things and then realizes that he doesn't have enough tools to get it to run right. And there have been plenty of posts on this and many, many other boards from guys discovering just that.

CarterBrocks are not bad carbs, there are just better choices out there today. Ones that don't require a set of drill bits to get to run right.

And I am not cleaning ANYTHING out of my carbs with a drill bit.

The only reason to run an Edelbrock carb on your car is if you need to knock some power out of it to slow it down.

why do these type of carb threads always boil down to carter vs holley vs demon, etc? it's just information; not an infomercial.

Exactly which of the above posts are more infomercial than information? The Engine Masters shoot-out where the CarterBrock came in last? The fact that the CarterBrocks have a well known off idle hesitation that other carbs don't have? The need for a set of special drill bits to fix the CarterBrock's calibration problems?

Wouldn't any open minded shopper want that information before they pulled the trigger on one of these carbs?

What really pisses me off is Edelbrock's head in the sand attitude. All of the time I spent talking to Edelbrock, the many hours spent trying to tune this problem out of Edelbrock carbs, Do you think Edelbrock doesn't know how to deal with this problem? I'd bet they do and they will not share the fix with their own customers. Their final word to me from Edelbrock was that it was the dyno operator's fault. How many times have you seen an engine on the dyno being tuned for off idle performance.?

Been running a 1407 since the eighties. Never had an issue other than a leaky float. Seems to me the issue isn;t a carb design defect but the application needs tuned to.

Seems the people complaining about having to tune a AFB, or whatever Carter you have, forget Holleys need tuning too. At least they do if you want something optimal and that goes for any "universal" type carb out there regardless of who made it.

You want something tuned specifically for your combo, run the factory setup. You deviate from that you will need to address the effects of those changes. You can do it yourself with a cheap set of bits or pay someone else to overcharge you to do the same.

But pissing and moaning about a non issue solves nothing.

Agreed. Only carb in my experience that hasn't needed a bit of tweaking is dead-stock OEM stuff.
The Eddy AVS2 on my '68 RR is a better piece than its 53-year-old AVS, and with a little cosmetic work, now looks very original.
Functionally, all I did was change the metering rods; that system's pretty clever and not hard to figure out.
For some builds, looking stock has a lot of appeal.
The Holley on my racecar has had a lot of work done to optimize it for its application, for that matter...

They're cheap, no excuse for not having the set.

https://www.ebay.com/itm/59Pcs-Prec...l-Bits-Set-Rotary-Tools-Kit/184437419802

I just pulled a spare 1405 (or was it a 1406? ) off the shelf.

A 0.028" drill bit is the biggest that will fit in the orifice. I'm also having an off idle stumble, so I may just drill them out to 0.035"