Carburetor Advice

[rdf]

Need some advice on a carb for my car.....it's a 73 'Cuda with a 440 stroked to a 493, headman headers, 452 steel heads, MSD ignition, distributor, and coil, 3000 stall converter, etc. etc., haven't dyno'd it but builder of the motor estimates 500hp+.  I'm looking to get a new carb for it and am open to suggestions.  The carb I have on there now is a double-pumper but I can't make out the manufacturer or model.  I've taken the entire carb off the car and there are no numbers or castings anywhere....but, I took it to a speed shop to get some tuning done to it and they said it was more of a racing carb vs a street carb, and recommended I switch to a street carb. 

I like Holley a lot but am open to suggestions/comments 

Just wanted to add; I've been on Holley's site and used their "Carb Selector" calculator to see what they recommend, it's in the 900 range, which seems a bit high to me.  Their calculator uses this formula: ((Engine Displacement X Maximum RPM) / 3456) which for me would be ((493x6500)/3456) = 927.228009 (I used 6500 RPM as a conservative number as I don't plan to race this car or be on it constantly at those RPMs.)

[70vert]

I suppose they may have guessed "race" carb because it is a double-pumper.
So that begs the question, are your plans to just cruise in the car (street)? If so I would agree that something with mechanical secondaries and electric choke would probably be better. If you are planning to race it then a double pumper is better, and still streetable.

I assume you don't know what size it is either? Even though you have stock steel heads a 700-750 cfm would be good on it. Holly makes several options. I am running a ProForm Street Series 750 on my similar 440 and it is perfect.

A picture of carb might help someone on here identify it.

[pschlosser]

By 1973, the factory was using Carter Thermoquad carbs, and I would stay away from those.

But in 1970, they were using Holley and Carter AVS carbs.  I recommend you go with one of the 440 HP Carter AVS carburetors, used in 1970.  The most common model is the 4966S, and they can be found used on eBay for a decent cost (prior to rebuild)

The Carter AVS is a 750 CFM carb, and will perform nicely on your motor.  The motor at 5000 is likely less than 750 CFM and may be a good fit to give you improved bottom end over a carb designed for 950 CFM.

For manual tranny cars, the risk of over-revving an engine may be higher, and the 750 CFM would help mitigate this danger.

I'm sure there are other pros and cons as well.  And while you may find a better carburetor to squeeze every foot-pound of torque from your motor, it may be hard to know for sure with some dyno testing.

The 4966 is my easy-way-to-go recommendation.

[Chryco Psycho]

A 750 AVS would be akin to running a 2bbl
I would recommend Proform 850 minimim , I usually go with 2x the CI so 950 would be the minimum I would use , the Proforms are very tunable & responsive  but the price is better than a Holley .
I have picked up HP using the 1050 dominator on 500 + Ci engines int he past & the dominators are also very tunable 
With my Duster I was shifting at 7200 rpm [440] & getting 15 MPG on the highway driving to the racetrack using a 1050 cfm Dominator .

[RUNCHARGER]

What Chryco says. 750 is a great carb for a 340. You need at least an 850 on a mild 500 incher.

[dodj]

I have a Quick Fuel 850 on my relatively mild 440. Works really well. I would go at LEAST 900 on your motor. CP knows his carb $h!t. But, to tell you the truth I would go FAST EFI or similar now rather than buy a carb. EFI is a little more, but not a lot more. When I bought my QF850, EFI was still too pricey.

[Chryco Psycho]

I agree EFI is far better , you get 1200 cfm that way & far better drivability .
Personally I prefer multiport EFI over T body / wet intake but the price is still very steep doing it that way .

[rdf]

I suppose they may have guessed "race" carb because it is a double-pumper.
So that begs the question, are your plans to just cruise in the car (street)? If so I would agree that something with mechanical secondaries and electric choke would probably be better. If you are planning to race it then a double pumper is better, and still streetable.

Definitely just gonna use it on the street....I have no plans on racing it in the near future.  As much fun as it would be to run it down the 1/4 mile, I don't think the setup (suspension, tires, etc.) is ready for that and don't wanna see it go into the wall.

I assume you don't know what size it is either? Even though you have stock steel heads a 700-750 cfm would be good on it. Holly makes several options. I am running a ProForm Street Series 750 on my similar 440 and it is perfect.

I spoke with my neighbor who gave it to me (came off his 69 Dart with the same motor build by the same guy) and he said it's a Holley 750 double-pumper.

[rdf]

A 750 AVS would be akin to running a 2bbl
I would recommend Proform 850 minimim , I usually go with 2x the CI so 950 would be the minimum I would use , the Proforms are very tunable & responsive  but the price is better than a Holley .
I have picked up HP using the 1050 dominator on 500 + Ci engines int he past & the dominators are also very tunable 
With my Duster I was shifting at 7200 rpm [440] & getting 15 MPG on the highway driving to the racetrack using a 1050 cfm Dominator .

Thanks for this info!  So it sounds like I need to be in the 850-950 cfm range, correct?  and I saw you comment below about EFI....I'll have to investigate to see if it's doable for me at this time....I really need to change my stock rearend cause right now it's like a unicorn on ice when I drive it.  I think a 4-link suspension will fix most of that but that's 4k easily.

[Chryco Psycho]

850 would be the absolute minimum , 950 is what I suggest , Proform has 850 double pump carbs .

I used to back 1/2 cars for racing , the 4 link is not the best IMO for what you want & is overly complicated to adjust correctly  , I would use a narrow diff with offset spring hangars adjustable shocks , clamp & add 1/2 leafs going forward only & use a double adjustable shock & you will be amazed at the traction with Good Dot Drag radials , if you want more used a floating ladderbar system , I pulled the front wheels for a decade on the street like this in my Duster . Probably just over $1K for ladder bars & shocks !