340 carburetor size?

[Tirekickertoo]

Hello,
What size single four barrel carburetor was installed on a 1971 340 engine. It is a factory stock engine with a 727 automatic transmission. The VIN# says it's a high performance engine but I think they were all the same, a sales gimmick? Anyways, would the four barrel carb be a 600, 650, 750cfm? What was the stock sized cfm carburetor installed on these engines when new?

Thanks for your help,

Tirekickertoo

 

[terrywalker]

Hello,
What size single four barrel carburetor was installed on a 1971 340 engine. It is a factory stock engine with a 727 automatic transmission. The VIN# says it's a high performance engine but I think they were all the same, a sales gimmick? Anyways, would the four barrel carb be a 600, 650, 750cfm? What was the stock sized cfm carburetor installed on these engines when new?

Thanks for your help,

Tirekickertoo

Carter Thermoquad rated around 750 cfm.
Terry

 

[Tirekickertoo]

Hi terrywalker, thank you for the reply. Initially I would of thought a 750 would be to big of carb, something designed for a big block engine. Interesting, Thanks for this information, I appreciate the help. Tire kicker too

 

[Rob C]

A member at FABO claimed he had actual flow rates of the TQ’s @ 737 cfm for the small 1.38 primary TQ and 787 cfm for the large 1.50 primary TQ.

Your early 340 would have the small one.

Replacing the TQ with a another carb @ 750 would be about right. FWIW, the older 340’s with the Carter square bore carb was an AVS @ 630 cfm as per the Carter tech line when they were still in biz.

 

[volunteer]

A member at FABO claimed he had actual flow rates of the TQ’s @ 737 cfm for the small 1.38 primary TQ and 787 cfm for the large 1.50 primary TQ.

Your early 340 would have the small one.

Replacing the TQ with a another carb @ 750 would be about right. FWIW, the older 340’s with the Carter square bore carb was an AVS @ 630 cfm as per the Carter tech line when they were still in biz.

Back in the day, I replaced the smaller, stock 625 (AVS) on my (stock) '70 with the larger 750 from a 440 HP. Had to do minor enlarging/chamfering of the primary intake holes, but definitely a power improvement. Keep in mind that the factory '70 (340) intake was the last of the square-flanges.
The (first year) T.Q. in '71 was different that the following versions in the way the fuel was metered. A better and easier to tune carb would be from a '72 or '73, or, the larger one from the '74 360.
As mentioned before, there were only two versions (sizes) of the T.Q. - as far as OEM marketed units. The 'smaller' one was used on 340's and 400's while the (HP) 360 and (HP) 440 used the larger one. There were many variances and external fittings and features that adapted each unit to whatever vehicle, ie: fuel inlets, EGR ports, canister purging, choke design etc.
I would never consider replacing a good T.Q. with anything else - unless deciding to go with square-flange style intake.

 

[1972 AAR Cuda]

I run a TQ on my 360 Challenger and I am very happy with the carb, but the motor is far from stock.