Anybody ever do a comparison between say a 72 340 carb and a 1000cfm comp. one? I started playing with a comp one (yeah, i know, i am cheatin sob), and it is down power all the way through. I havent gotten the tune exactly right yet, but it is far enough off for me to wonder if it will even match the 72' carbs numbers.
Carter Thermoquads ~ 'More General Information'
- Thread starter 69 Cuda 440
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EL5DEMON340
Well-Known Member
Not that I know of, the 71 340 and comp are fuel metered all the later quads air metered. Maybe that's the difference? But I have spoke to guys running the 71 340 carb that swear it's a bit "faster" than the later ones. I've got jets and rods for the early ones but haven't played with the t-quads yet my 6 pack kicks butt.
Carter Thermoquad
'1975' 360/230 HP Engines
TQ-9002
Primary ......... 1 1/2" {1.500"} ......... Venturi = 1.186"
Secondary ..... 2 1/4" {2.250"}
Primary Jets ........ .095"
Secondary Jets .... .143"
Metering Rod ....... 1998 {.075" Economy ~ .057" Mid-Range ~ .040" Power}
Needle and Seat ... .0935"
CFM Rating ....... 787 CFM's
'360' Intake Manifold ... #3830945
The '1975' units were equipped with >
* IES {Idle Enrichment System}
* TPS {Throttle Position Solenoid}
The {IES} is for drive-ability enhancement, which allows for a 'richer mixture'
during the warm-up period, as the system blocks part of the choke air-bleed to
richen the Air/Fuel mixture.
The {TPS} delays 'full-throttle' closure at deceleration, to prevent a rich condition from developing.
The 1975 Thermoquad's ran with a 'leaner' primary, as evident by the
'fatter' Metering Step-Rod {.075" Economy}
'1975' 360/230 HP Engines
TQ-9002
Primary ......... 1 1/2" {1.500"} ......... Venturi = 1.186"
Secondary ..... 2 1/4" {2.250"}
Primary Jets ........ .095"
Secondary Jets .... .143"
Metering Rod ....... 1998 {.075" Economy ~ .057" Mid-Range ~ .040" Power}
Needle and Seat ... .0935"
CFM Rating ....... 787 CFM's
'360' Intake Manifold ... #3830945
The '1975' units were equipped with >
* IES {Idle Enrichment System}
* TPS {Throttle Position Solenoid}
The {IES} is for drive-ability enhancement, which allows for a 'richer mixture'
during the warm-up period, as the system blocks part of the choke air-bleed to
richen the Air/Fuel mixture.
The {TPS} delays 'full-throttle' closure at deceleration, to prevent a rich condition from developing.
The 1975 Thermoquad's ran with a 'leaner' primary, as evident by the
'fatter' Metering Step-Rod {.075" Economy}
6138S {1972 '340/240' HP} ............................. 4847S {'Competition Series'}
Primary ..... 1 3/8" {1.375"} Venturi = 1.073" ....... 1 1/2" {1.500"}
Secondary .. 2 1/4" {2.250"} ............................... 2 1/4" {2.250"}
Primary Jets ..... .095" ......................................... .089"
Secondary Jets . .137" ......................................... .116"
Metering Rod ..... {.070" ~ .046" ~ .040"} ............. {.064" ~ .030"}
Needle and Seat ... .0935" .................................... 1.250"
Advertised CFM Rating ... 800 ................................ 1000
Actual CFM Rating ......... 737 ................................. 915
For the 'Street'.
Obviously the #6138S is the way to go.
But at the 'Strip', the Competition Series is designed to run at W.O.T.
The 'thinner' Metering Rod {.064" ~ .030"} allows for a richer Air/Fuel mixture,
and the single-booster ring for the Primary allows for more air-flow thru the
1 1/2" Throttle.
You can also step up the Jet sizes 'much bigger' on the Competition Series, with
a less over-rich condition.
They require some time consuming tweaking, but when they are right.............:burnout:
The thing about the BIG TQ is it is overkill on many engines. You still need to size the carb to the engine with its intended useage.
Primary shot. Notice the barrel(s) are just big bore holes and the single ring booster on this carb. A poor signal will result, unless the engine is big enough or ignoring low end and idle. The larger the engine, the easier it would be to find a suitable idle with this carb.
Here is the underside. It becomes easier to see why idle can be tough to set on a small and/or a mello engine. A primary of this size can power an engine quit well on its own. If your car doesn't respond with a quicker ET with a bigger carb, then generally speaking, it's to big.
Sorry for the blury cell photos
Sorry for the blury cell photos
Thanks Rob,see what you mean on sizing,& circuits.
Excellent photo's Rob
And excellent information.
Also, the Primary nozzles {squirters} point 'downward' in the Competition Series, as opposed to 'up' in the regular Thermoquad Carburetors.
And excellent information.
Also, the Primary nozzles {squirters} point 'downward' in the Competition Series, as opposed to 'up' in the regular Thermoquad Carburetors.
You have it reversed, sir. The 71 was the air metered. The rest were solid fuel metered. I am not familiar with how the comp models were metered though.
That Is Correct,
The 'Competition Series' and 1971 Thermoquad Carburetors use the 'conventional'
Air-Bleed Metering System.
Air is introduced into the Fuel Stream {before} the Fuel discharges from the Nozzles.
1972 and later Thermoquads > are 'Solid Fuel Metered', which means that the Fuel
Metering System feeds the Primary and Secondary discharge nozzles with a continuous
stream of fuel that mixes with the Air {after} it leaves the nozzle.
Frito,
A good Thermoquad choice would be off the 1973 '400' {Automatic Transmission}
#6321S
Primary ............ 1 1/2" {1.500"} ...... Venturi = 1.186"
Secondary ........ 2 1/4" {2.250"}
Primary Jets ...... .098"
Secondary Jets .. .137"
Metering Rod ...... 1966 {.067" Economy ~ .052" Mid-Range ~ .045" Power}
This Thermoquad will outperform a 'Competition Series' 850 CFM.
A good Thermoquad choice would be off the 1973 '400' {Automatic Transmission}
#6321S
Primary ............ 1 1/2" {1.500"} ...... Venturi = 1.186"
Secondary ........ 2 1/4" {2.250"}
Primary Jets ...... .098"
Secondary Jets .. .137"
Metering Rod ...... 1966 {.067" Economy ~ .052" Mid-Range ~ .045" Power}
This Thermoquad will outperform a 'Competition Series' 850 CFM.
Just for clarity, the "Competition 850" you mention is the electric choke aftermarket version?
Are you referring to the #9800's 'Superquad'
* Electric Choke
* High-Flow Metering Rods
* Larger Jets
* Wide > Needle and Seat
That was my question to you. To define what carb you were talking about. I am unclear. I thought you may have been mentioning the above carb.
EL5DEMON340
Well-Known Member
I thought I had it backwards, but figured someone will correct me. I'm starting to forget more than I know about these. And I still have a bunch of 71 carbs LOL.
Me too man. I need to start writin some of this down. LOL
Hay, who you callin Frito? LOL
A Thermoquad #6321S {stock} will edge out an early {Competition Series} CS-4846S
out-of-the-box and untouched.
The #1966 Metering-Rods in the #6321S are the 'good ones'.
{.067" Economy ~ .52" Mid-Range ~ .045" Power}
The #6321S is a 'gem' if you can find one.
Ooooo
Gotcha!!!!
Gotcha!!!!
Captainkirk
Old School Mopar Warrior
Thanks for this info. Good to know!
A sneaky good Thermoquad .... #6321S
Off of the 1973 '400/260' HP {Engine Code; 'P'} Automatic.
Model ............................... Production Numbers
1973 Road Runner ...................... 1991
1973 Dodge Charger Rallye .......... 2345
Frito,
Is a salty corn chip. It can be eaten plain, or with a dip {ie; Ranch, French Onion}
or Salsa.
You cannot eat just one.
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