My Carter B&B carburetor body is porous??

[Dave72dt]

You don't by chance happen to use SEAFOAM in your tank.   It's commonly used as a fuel additive for cars in storage over winter and that stuff will creep uphill.

[D35 Torpedo]

My car had a bracket so i used it...right or wrong. A sponge will carry water to the top of it as well through capillary action.

[motoMark]

Back to the gas issue. After I started and ran the engine for a few minutes, I saw some gas pooling in the now usual places around the airhorn gasket and adjoining surfaces, as expected. I also saw some wetness down below on the gasket between the carb body and the lower spacer plate. At that point I figured I'd just take the damn carb off and have a look at in on the bench.

 

Gradually I took the carb apart (airhorn, spacer plate, throttle plate) while looking for anything obvious. Didn't notice anything. So I'm left with the float bowl in my hand, which still has gas in it. Removed the float, accelerator pump and the jet/needle assembly thing and set the bowl on the bench. The top gasket surface of the float bowl is still wet so I wipe it off repeatedly. And repeatedly it becomes wet again.

 

Then I dumped the gas out of the float bowl and dried it out with compressed air. The inside walls of the float bowl look kind of rough in my opinion, and seem to have a fair amount of pits and voids (see photos). Granted, I know the surface isn't supposed to be precision smooth, but they look rougher than I expected.

 

Then I took some fresh gas and poured about 1/2" of it into the bowl and watched. You'll notice in the photos how dry and almost chalky the float bowl looks. Well, as I'm watching it, I see the gas wicking it's way up the walls of the float bowl. Not fast, but it's happening. There is a distinct "wetness line" creeping its way up the walls. Eventually I see gas pooling again on the top gasket surface.

 

So by everything I've seen, I have to conclude that the casting is porous. Maybe it was ok when it was made, but over time deteriorated? I don't know. I think it's new carb time.

 

 

[Ivan_B]

Didn't try using sealant on the gasket, yet?

[Dave72dt]

Perhaps someone else can repeat the experiment on one of their carbs and report back.  I don't have any carbs floating around or I'd try it myself.

[D35 Torpedo]

1 hour ago, motoMark said:

Back to the gas issue. After I started and ran the engine for a few minutes, I saw some gas pooling in the now usual places around the airhorn gasket and adjoining surfaces, as expected. I also saw some wetness down below on the gasket between the carb body and the lower spacer plate. At that point I figured I'd just take the damn carb off and have a look at in on the bench.

 

Gradually I took the carb apart (airhorn, spacer plate, throttle plate) while looking for anything obvious. Didn't notice anything. So I'm left with the float bowl in my hand, which still has gas in it. Removed the float, accelerator pump and the jet/needle assembly thing and set the bowl on the bench. The top gasket surface of the float bowl is still wet so I wipe it off repeatedly. And repeatedly it becomes wet again.

 

Then I dumped the gas out of the float bowl and dried it out with compressed air. The inside walls of the float bowl look kind of rough in my opinion, and seem to have a fair amount of pits and voids (see photos). Granted, I know the surface isn't supposed to be precision smooth, but they look rougher than I expected.

 

Then I took some fresh gas and poured about 1/2" of it into the bowl and watched. You'll notice in the photos how dry and almost chalky the float bowl looks. Well, as I'm watching it, I see the gas wicking it's way up the walls of the float bowl. Not fast, but it's happening. There is a distinct "wetness line" creeping its way up the walls. Eventually I see gas pooling again on the top gasket surface.

 

So by everything I've seen, I have to conclude that the casting is porous. Maybe it was ok when it was made, but over time deteriorated? I don't know. I think it's new carb time.

 

 

To me, that all looks fine. Perhaps your local gas pump is adding something to the gas, wouldnt surprise me one bit. The fuel isnt pouring out the side of the carb, so cleaning up the gasket surfaces to a smooth finish and make sure they are true. Use JB weld to body work the gasket surface if you have to. Also, use a fresh gasket..

Edited April 25 by D35 Torpedo

[Dodgeb4ya]

Ever seen water get pulled way up a leaking low slope roof ?

Capillary attraction between layers of roofing.

Could happen to a porous casting.

[motoMark]

8 hours ago, Ivan_B said:

Didn't try using sealant on the gasket, yet?

Not yet. But I see Permatex makes a fuel resistant gasket dressing/sealant, so I think I'll give that a try.

[Dartgame]

Test the permatex dressing you are talking about, by letting some dry on a piece of aluminum overnight. Then submerge it in jar of gas for a few days and see how it behaves. It would be a mess to have a sealant get sucked into the jet and emulsion tubes etc.

[Ivan_B]

2 hours ago, Dartgame said:

It would be a mess to have a sealant get sucked into the jet and emulsion tubes etc.

If you use the proper amount (which, literally, no one does), it ain't going anywhere

[Sam Buchanan]

A sealant I've used for a long time both automotive and aviation is Permatex #2. Yes, apply a very THIN film on both sides of the gasket after you have determined both sealing surfaces are flat and true. Silicone sealants (RTV, etc) are not recommended because a tiny glob of it might get into a jet and not dissolve.

[motoMark]

Update on the carb weep situation. Over the weekend I bought the sealer I mentioned earlier and applied it to both sides of the gaskets as well as a thin coat on the gasket surfaces. The instructions say to wait until the solvent flashes off before you assemble the components, so that's what I did. It was a little tricky applying the sealer on the carb itself because you don't want to plug up any air passages or leave any big blobs. But I was careful not to do either of those. Slapped it all back together, bolted it to the engine and fired it up.

 

So far it seems ok. I've run it a few times up to and at operating temperature, and I don't see any puddling where I saw it before. I'm hesitant to say it's all fixed, but I'm happy with the overall results with the sealer. Once I get a chance to drive it, I'll hopefully have a better idea whether it's fixed or not. But for now, I'll call it a win.

 

 

[Ivan_B]

11 minutes ago, motoMark said:

So far it seems ok.

Told ya

 

But it looks like you did use a bit too much. And there is usually no need to smear it around the parts themselves when you are simply using it as a gasket dresser. What I usually do is wear a latex glove, take a small blob of sealant between the two fingers and spread it around the gasket, on both sides simultaneously. Turn it around, and repeat, adding more sealant to my fingers as necessary. If you later take it apart, and want to reuse the old gasket, you can always wash it with carb cleaner and a rag in a similar fashion.

[motoMark]

On 4/28/2024 at 9:06 PM, Ivan_B said:

Told ya

 

But it looks like you did use a bit too much. And there is usually no need to smear it around the parts themselves when you are simply using it as a gasket dresser. What I usually do is wear a latex glove, take a small blob of sealant between the two fingers and spread it around the gasket, on both sides simultaneously. Turn it around, and repeat, adding more sealant to my fingers as necessary. If you later take it apart, and want to reuse the old gasket, you can always wash it with carb cleaner and a rag in a similar fashion.

The reason I applied the sealer to float bowl gasket surface as well was to hopefully prevent gas from pooling on that surface. In a normal situation I would not do that, but this situation is certainly not normal 🤪

[Ivan_B]

Ok, still no leaks, I assume?