best carb for 340?

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IMO, I would sell that carburetor and go to the Thunder 650. That carburetor you have now is an AFB style and is far inferior to the AVS style. The AFB has the secondary air door below the secondary boosters. The AVS secondary door is above the boosters. This allows much more of an accurate signal to the boosters and allows for a much smoother transition into the secondaries and allows for greater adjustability. All of that, plus the extra 50 CFM and you'll be right on top of what you need for that engine, IMO. Others may disagree and say you can run a 750. You probably can but it will require more tuning to get it right, IMO with that gear you have. I think the 650 Thunder AVS is a perfect match.
 
How about the stock Carter AVS? Chrysler seemed to like them enough to put them on most of their muscle cars.
 
Absolutely. I didn't get the impression he had one layin around. If he's gonna have to buy something, the Thunder AVS would be a vast improvement.
 
hi, I see the lowly carter AVS and T.Q. are kinda bashed about. in world of stk and S/S , you use the original carb!!! right now, there are 340's 1970 with AVS going 10.7 secs, also 72 and 73 340's going 10.70 with T.Q.carbs.
these are stockers!!! also matt steen's 235 /273 SS/K car with small AFB, runs mid 10 sec and 120 MPH!! like was stated , you have to know about fuel curvres in a carb. on a T.Q. only thing done to tune is to lowere or raise the metering bar for prim and open or close the air door , sec side. very easy to do. holley is not the all mighty!!!!
 
perfacar said:
hi, I see the lowly carter AVS and T.Q. are kinda bashed about. in world of stk and S/S , you use the original carb!!! right now, there are 340's 1970 with AVS going 10.7 secs, also 72 and 73 340's going 10.70 with T.Q.carbs.
these are stockers!!! also matt steen's 235 /273 SS/K car with small AFB, runs mid 10 sec and 120 MPH!! like was stated , you have to know about fuel curvres in a carb. on a T.Q. only thing done to tune is to lowere or raise the metering bar for prim and open or close the air door , sec side. very easy to do. holley is not the all mighty!!!!
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And what carb has the most tune-ability out of them all?
 
I didn't see anybody bashing any carburetor. Maybe I'm lookin with the wrong eye.
 
And what carb has the most tune-ability out of them all?
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From the average Hotrodders perspective it would be the holley, but that doesn't mean its the best.

It takes a lot more knowledge to tune a TQ or Qjet due to the design principles used to overcome the inherent design problems carburettors face.

Hysteric
 
650 DP Holley or a 750 VC Carb IMO :burnout: :glasses7: :prayer: :burnout: :D
 
I think you would be surprised how well the 600 would work.
The car should run clean and crisp with it,with only the top end down a little.
Having said that,I run the 650 AVS on my mild 360.














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Run the numbers on all the online calculators. Anything above a 650, unless it's something like a Thermoquad is simply way too big.
 
I'm running a Thunder Series 650 on my 340 and it works really well. The only problem is it going dry after sitting a few days. Seems like I use more fuel by evaporation than I do by driving it.
 
I have a 650 AFB on top of a 383 in my 69 A-100 works dam good for toot'n around town. Nice and crisp throttle response. Although I much prefer the Pro-form 650 for tune ability.. I find that the oil is a lot cleaner for a longer periods of time with the AFB. Helps extend the ring life of ole girl. :)
 
I'm running a Holly 650 DP with a LD340 on a basically stock engine and really like it.
 
if you take the time to learn and understand the Thermoquad it will be almost imposable to beat as a true all around performance street carb, and with the right set up will run with most all so called up grade carbs ...old black magic
 
So i aquired an 750 4150 off my buddy who swears by them.. hes going to set it up for me when the motor is ready to run thanks for all your input on this.
 
So long as you tune that sucker up right, it'll be a scream for ya. (AKA work well)
 
The 1406 is too small to make a 3.23 SG 2800 convert to catch low 13s in the 1/4, even hard at sea level on a wicked tune. They are not a 650cfm carb. Some of the AVS are, vary between 625 and 650, depending on which one you've got.

They do make a bigger AFB, but on this run, if you don't mind monkeying, a TQ would be boss. You can get primaries and new plastic bodies for them, if need be.

If not, Skrews suggestion would be a great choice.

The Street Demon is wet CFM tested at 625. I don't know if Holley is producing dry or wet CFM numbers on their carbs, but on their Demon units, they are. The AFB is dry CFM rated, which is going to drop a bit once fluid is introduced to correct it.

A 1406 wet/ corrected CFM rating is down in the mid 500s. That's a 60 year old design and the CFM testing is rated with air, only, old numbers.

For a 13 second engine, you want 700cfm rated dry, or better if you can find a carb that is designed and rated with wet cfm.

Give that 4150 a go.
 
DaveBonds said:
The 1406 is too small to make a 3.23 SG 2800 convert to catch low 13s in the 1/4, even hard at sea level on a wicked tune. They are not a 650cfm carb. Some of the AVS are, vary between 625 and 650, depending on which one you've got.

They do make a bigger AFB, but on this run, if you don't mind monkeying, a TQ would be boss. You can get primaries and new plastic bodies for them, if need be.

If not, Skrews suggestion would be a great choice.

The Street Demon is wet CFM tested at 625. I don't know if Holley is producing dry or wet CFM numbers on their carbs, but on their Demon units, they are. The AFB is dry CFM rated, which is going to drop a bit once fluid is introduced to correct it.

A 1406 wet/ corrected CFM rating is down in the mid 500s. That's a 60 year old design and the CFM testing is rated with air, only, old numbers.

Yep will do..when proper jetting and tuning apparently will do good!

For a 13 second engine, you want 700cfm rated dry, or better if you can find a carb that is designed and rated with wet cfm.

Give that 4150 a go.
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Yep will do good with the 4150.. when tuned and jetted right i will make good power!
 
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