71 TQ is unique and prone to issues. 72 and up were redesigned to fix the issue...
Many of the 71 carbs were replaced under warranty by 72 carbs by the dealers.
This was because of drivability issues!
This helps to explain why they are hard to find.
I do not recommend them for a daily driver
The best performance calibrations were the 9800 followed
by 9801/9810/9811 all aftermarket Super Quads.
Cores for those can be found $200 to $300.
The emulsion tubes are a restriction to metering on every
OEM supplied Thermoquad for racing and nearly impossible
to change or drill without ruining them completely!
I have been racing these since new.
Google: John Irving Drag Racer