I'm having flooding problems with a Stromberg SF-4, and am confident that it is not a float problem, or the needle and seat. It seems to be pulling gas through the accelerator pump circuit. Are these carburetors subject to this? The carb is clean, passages are clear, I installed a rebuild kit and it ran perfectly for 500 miles before the first instance, and now does floods continually. There is no gasoline in the float itself, or leaks out of the bowl. Any suggestions?

Jr,
A couple of general carb thoughts. Is the float level set too high? Is there a stuck open accelerator pump discharge check valve (if it has one)? If the accelerator pump has a removable discharge nozzle, is the gasket cracked/broken, nozzle not tight? Not sure the vintage on this carb, but if fuel pump fed,is the fuel pump pressure incorrect? Do you have a drilled passage where a plug has come loose (usually for pressed in type plugs)? I've rebuilt DD-3 and EE-3 types but not sure of the one you have. Can you possibly check the fuel inlet needle seat to body area for fine cracking? Maybe block off the seat and test with some air pressure.

Is your fuel line located close to the engine block or exhaust? If there's a lot of heat getting to the line you may have gas being vaporized in it, pushing the rest through the line into the carb and flooding it. Today's gas will boil at very low temps, sometimes near 100 degrees F., boiling dry at no more than 170 degrees F.

A solution has emerged, thanks to Carb King (I couldn't remember his user name earlier; it's not Carb Doc). I spoke to him today and he suggested checking out the vacuum tank. We pulled the line from the tank to the intake manifold, and it was full of gas. The engine was pulling so much raw gas into the intake manifold that it was flooding out, and the raw gas was then running down through and out of the updraft carburetor -- creating the impression of a sticking carb float. Thanks for everyone's help. If not for the Forum, I wouldn't have known about Carb King. Now, does anyone know who the vacuum tank guru is? I've had the tank apart before, and know that I need a part or two.

If the float has a leak it will allow gasoline inside it making it to heavy to float to the proper level, thus over filling the vacuum tank with gas. This gas will then overflow into the vacuum line and then into the intake manifold.

Tom check the float for leaks simply remove it and shake it. If there is gas in it you will hear it slosh around.

Another method is to place the float into a pot of very hot (near boiling) water. The air escaping from the float will be easily visible.

If the float is in good repair make sure the mechanisms it attaches to inside the vacuum tank are not stuck. I doubt that is the problem though and regret to say odds are good the float is leaking air and has a little gas in it.

You are welcome, and I am glad you found the problem.

The Antique Auto Parts Cellar in Boston has some vacuum tank parts.

Jon.

Gary Wallace also sells vacuum tanks and parts.