I have a 71 'cuda with a 340 4 speed. The engine is built largely to stock specs with a slighly larger cam. The Thermoquad on it is a '73 340 carb that was rebuilt two years ago. After taking the car out for its first drive of the spring, it started running terrible. I could hardly get it started to drive it home after stopping at a store near my house. It appears to be flooding. When I got it home, I popped the hood and there was gas leaking almost everywhere from the carb (both above and below the resin body, from the accelerator pump opening, from the throttle assembly, between the carb and manifold). Gas was pooled in the low areas of the intake manifold.

I tried tightening the screws that hold the body together and they all appear to be tight. What would cause this? Did the gaskets dry out and shrink over the winter? Would stuck floats cause this?

I'm going to pull the carb apart and rebuild it again, but don't want his happening again in a year or two. Any thoughts?

Dropped floats would definitely cause all of that. If it sat all winter without being started occasionally, and without the right amount of fuel stabilizer in it, then the gas in the line and bowl also could have evaporated leaving a bunch of yellowish crusty crud in the carb which could clog the needle and seat (flooding) as well as the jets and rods (poor idle and performance). Either way, probably needs a rebuild.

If it has brass floats shake them to see if you can hear fuel in them, if not use a pair of pliers to emerse them in water just off of boiling. The hot water will expand any air in the floats and cause bubbles to rise from any pin holes in them, which are usually in the solder between the two halves.

May have dirt on the needle and seat as it sounds like its flooding. May also have a heavy float but how far did you drive it and how hot was the eng ? Ron

take off the tree/rods etc then the top to get at the innards & see if there's a bunch of crud (as said rebuild if it is that bad or just blast out the bowl with a can of brake kleen) as (if) needed. Wouldn't hurt to replace the needle/seat assys while you are in there with some good quality pieces. If TQ needles/seats are seperate (iirc they are) then twirl the tapered neoprene tip on the seats in between your thumb/forefinger to smooth them (that's my OCD talkin) and be sure to blast the seats. As said check your floates & a good procedure was posted above. Short version: replace the filter with a Wix/twirl the needles/inspect the bowl/check/reset the floates.

First of all, the gas pouring out everywhere is almost certainly a stuck open needle/seat.

Causes:

Float is either stuck to the bad gas in the bottom
Float has a pin hole and has sunk
Float is not properly adjusted
Needle seat have something between them allowing fuel in when closed
Needle and seat are bad allowing fuel in when closed

Bad gas from sitting can cause several of the above symptoms, I'd suggest removing the fuel tank, having it boiled and sealed out or replace it. Clean out the fuel lines, fuel pump, and change the filter. It's a PIA but the only way to know you've fixed the issue completely.

Whatever you do, don't clean the carb with Brake clean. Use carb cleaner.
Brake clean does bad stuff when it burns, the fumes can kill you. Gene

gene is deadly serious with this comment, and i'm not making a pun. brake cleaner when burned creates phosgene gas, similar to mustard gas. don't take much of this stuff to do you in. guys get real sick and can die using brake clean to clean up stuff before welding. a warning to not take lightly !!

I never gave that any thought (till now) as I treat all chemicals as toxic (especially the ones that flash off/vaporize quickly) but I went into the kitchen & looked at the can of brake kleen and it is non chlorinated so I think I'm good (& no I don't use it inside!). Just me I dont see a problem with blowing out the carb bowl with it even if it was chlorinated tho my favorite brand (cheap) is no chloride (done it many times) in a well ventilated area tho (car near the shop door/door open)

Car near the shop door is not outside, now that is living like it is your last 24 hours! LOL.

Carbon monoxide is colorless and odorless. Stop fooling yourself, get the car outside.

Read this if you need more info on CO

http://www.abe.iastate.edu/extension-and-outreach/carbon-monoxide-poisoning-garages-aen-207/

https://gtautomotiveutah.wordpress.com/2...xide-poisoning/

Use carb cleaner, not brake cleaner. Do you have brakes in your carb??? I wouldn't recommend burning any type of brake cleaner. There is a difference between carb cleaner and brake cleaner...they make both for a reason. And definitely don't run the car indoors. Any of these things can be hazardous if used improperly.

And guess where a lot of that gas has gone...down into the intake. So when you first fire it up, it will probably be extremely rich (high CO).

(1) excellent humor brother (for real) (2) I did not mean running the car next to the door I meant having it next to the open door when spraying chemicals (such as my non chlorinated Brake kleen) into a carb bowl to blast/clean it out