Carb Float

Hello all. The carbs on my 79BB are currently being rebuilt, as part of an entire engine out service/refresh, and upon inspection, one of the brass carb floats appeared to be crushed or imploded, badly. Since the car is in Houston, and not exposed to any freezing weather, I'm puzzled as to what conditions might cause this?

Sam

 

I'd be interested to hear some theories, because 19271 (which was also a Houston car) had a similar ailment.

 

I've seen this also, hard to understand . Maybe it was so hot when it was soldered together that it had a vacuum when cooled, then an extra high pressure day below sea level did it in.

Just a theory.

 

Just remembered. Most likely cause is compressed air. You have to be careful with air blowers around carbs. If air was directly pointed at one of the vent tubes even inches away it would be pretty easy to crush a float.

 

The float was defintiely mis-handled at some time in the car's life. New floats set on parts shelves for years without any damage, so there is no doubt that either compressed air, or an idiot was responsible for the damage.

 

How about a needle valve sticking open occasionally? Don't know if a few psi is enough to crush a float (and a lot of other bad things would happen ), but might depend on the float design...

 

Well, a new floats on the way. Thanks for the observations, I just wanted to make sure it wasn't something systemic that would cause this to happen again. I'll have to check the welds again, perhaps it perforated somewhere.

 

Float chambers are not sealed. To start with even a small rise in level so much fuel would go through the main circut it would flood the cylinder.


I agree with Dyke, someone in Texas was hard on floats.

 

It's like the school science experiment where you heat a metal container, and then screw the cap on. As the container cools, it implodes. The float probably had a pinhole that opened when it got hot, probably after the motor was shut off, and no cool fuel was flowing past. As the float started to cool, the hole closed. As it cooled more, the negative pressure caused it to implode. If the pinhole was on the bottom of the float, it would suck in fuel. Haven't you ever seen a carb or sending unit float that had mysteriously filled with fuel, yet no fuel drips out?

My 2 cents. I'm really here to drool over Newman's awesome Boxer resto. No updates, bummer.