I'd like to add one more important fact:
In every reference database about TQ carbs, they mention early carbs being air metered, and later carbs being solid fuel metered, then another thread elsewhere on the net states the difference is, solid fuel metered TQ carbs add air after the fuel is discharged from the nozzle. air metered TQ carbs add air before the fuel is discharged.
that is simply incorrect, and somewhat misleading. they both add air before the fuel is discharged, using air bleeds in the air horn, in the same place. the later carbs just add more air at the nozzle as well.
I have both types of carburetors, looked at them closely. there is only one slight difference between the 2 types.
1. the early carburetors pre-'72 have 8 air bleeds in the top lid. 2 are in the primary bores above the venturis, one per side in the front corners, pointing inward above the nozzles. these can flow both ways. air can be pulled into idle circuit, or fuel can be pulled out at certain velocities into the venturi. there's also one idle air bleed on each side near the primary metering rods, in corners of the top cavity, exposed.
there are 2 more per each side under the plates where the metering rods go down through the lid in that same cavity. if you remove the plates you can see them. 1 is for primary main metering, 1 is for secondary main metering. they are the small tiny ones going straight down. so there is a total of 8 air bleeds in the early CS carbs. there are no air bleeds in the nozzles themselves.
2. the later '72-up carburetors have those same 8 air bleeds, but the idle air bleeds are not in the primary bores, instead they're relocated to the venturi, a large air bleed in the nozzle itself. but it's not mixing the air with the fuel AFTER the fuel exits the nozzle. it's putting air into the nozzle and mixing it with fuel INSIDE THE NOZZLE. there is still an aerated/emulsified mixture exiting the nozzle, just like the early CS carbs- only it is emulsified to a higher degree. this is the same thing Barry Grant did to the Holley design when he released the Demon carbs- he added extra emulsification bleeds to the metering blocks. where Holley only had 2 bleeds per barrel in the block itself, BG had up to 5 per side.
3. the holes in the primary rod guide holes in the top of the carb on the early CS models, go directly down into the main jet well. when those rods are pulled up out of the holes at WOT, the space between the primary metering rods and guide holes also becomes an air bleed. any holes above float level into metering passages become air bleeds of sorts. and holes below float level are fuel metering. on some designs a fuel metering hole may be uncovered at WOT, and become an air bleed at higher rpm- and vice versa.
this is nothing out of the ordinary. the TQ is an improved Qjet carb design, improved with more airflow, 2 floats, 2 needle valves, 2 larger fuel bowls, and will generally support a somewhat higher HP output than a Qjet-at least on paper- due to increased fuel/air supply and flow. if you ran a 1972-up Mopar in NHRA SuperStock, you must run a TQ per the rules- how bad can they be ? the Qjet also has air bleeds at the nozzle, just like the TQ, the Qjet had them from day one. and they also do quite well making 600-700HP+ in SuperStock no problem.
the correct description of the pre-'72 TQ carbs would be, "without nozzle/booster venturi air bleeds".
the later 1972-up carbs do not add air to the fuel after the fuel discharges from the nozzle. it adds air before that point just like any other carburetor does with the air bleeds in the same position- what it does is, adds more air AT THE NOZZLE internally, before the a/f mixture is discharged.
take a look at the 2 types closely with a bright light, and remove the upper plates, and look closely in the bores, etc. inspect the nozzles, there is an air bleed on top, discharge hole on bottom. as the fuel enters the tip of nozzle, it pulls air through the upper hole, both air and fuel exist the bottom together. the point of all this, air was introduced prior to the nozzle, far upstream, by the air bleeds at top of air horn, near the primary metering rods.
Holley high performance racing carbs typically have no air bleeds at the nozzle, just hole for fuel to discharge from. neither does the secondaries on the Qjet or TQ.
