Carter Thermoquads ~ 'More General Information'

Carter Thermoquads

First found on the 1971 Mopar 340/275 HP Engines.

* 4972S {Manual Transmission}
* 4973S {Automatic Transmission}

* Primary ....... 1 3/8" {1.375"} ........ Venturi = 1.063"
* Secondary ... 2 1/4" {2.250"}

'Originally' advertised at 800 CFM's, but numbers were closer to a 'tad' under 750 CFM's.
at 737 CFM's.

This Carburetor replaced the Carter AVS {630 CFM} that was found on
the 1968 -thru- 1970 340/275 HP Engines.

With the 'new style' Cast Iron Intake Manifold {1 3/8" Primary and 2 1/4" Secondary}
Throttle-Bore openings with the 'Butterfly-design', this combination put out more
Horsepower on the 1971 '340' than the 'earlier' Intake and Carburetor of
the 1968 -thru- 1970 '340'.

The 1971 Thermoquad came thru with ;
* Primary Jets ....... .074"
* Secondary Jets ... .125"
* Metering Rod ....... 655 {.062" Economy ~ .040" Power}

* Needle and Seat ... 0.0935"

Generally, the 1 3/8" Primary Throttle-Bore provided for a 'smoother' and better throttle response on the Bottom-End.

On the CFM Rating >
'Carter Carburetor' stated that the Primary-Throttles delivered flow in the range of 225 CFM's, while the Secondary-Throttles provided +500 CFM's.

Netting {in the range} of a Total of 737 CFM's.

'1971' 340 Intake Manifold ....... #3512100
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'Thermoquad'

Comprises of '3' Main Sub-Assemblies

A} Aluminum-base Throttle Assembly
B} Phenolic Resin Main-Body
C} Aluminum Fuel Bowl

This combination, provides for up to 20% {24* to 28*} 'cooler' Fuel Temperature in the 'Fuel Bowl' than a 'conventional' all-Aluminum Cast Carburetor.

Advertised as;
* An 'emission-capable' Carburetor
* Superior 'fuel-economy' with smaller Primary Throttles.
* Excellent 'Top-End' performance from the larger Secondary Throttles.
* Minimal external emission attachments

The 1971 Thermoquards were 'Air-Fuel Metered'.

Also, the Primary-Jets were located in the Upper-Bowl cover, and
were pressed-in with O-Rings.

The Secondary-Jets were located in the Main-Body, as they were
with all Thermoquads.