I have a 440 with thermoquad carb and torqueflite auto transmission. When I brake hard the engine stalls. Normal driving is fine and it ticks over nicely when stationery. I’ve checked the floats in the carb and they seem to be okay. Any ideas what may be causing this?

 

Sounds like the float level is still too high to me..... Just my opinion...

 

Those Thermoquads at their best ran poorly. Try braking hard in neutral. If it doesn't stall you may have a converter that's not unlocking right away. My first thoughts are the float settings too.

 

Sorry but those Thermoquads rip when set up correctly! I personally would like to set up a pair of them on a tunnel ram, I have a 440 that I believe handle them perfectly.

 

I always had good luck with Thermoquads... However, when you whined up needing some parts that are hard to find for them, It's easier to swap to something else...

 

There was a time when power valves that tolerated ethanol were hard to find, at least for me. Id have to buy a kit to replace the valve, this was 40 years ago I would hope that is different now. Overall I believe the thermoquad is a good cab for a street engine.

 

Those Thermoquads were on the 360 and 400 engines in the 70s. I recall working on a fleet of cruisers with the 400s. They ran awesome wide open but at slower speeds cruising the streets all the cops complained about them. The 400 2 bbls with a larger venturi compared to the very small primaries on the Thermoquad weren't as fast but drivability was much more responsive and better during regular street driving until an unknowing person overtightened the air filter and would warp the airhorn and cause fuel to spray wildly down the carb. Thermoquad, just not my favorite.