epoxy sealing a brass carburetor float?

[hansp77]

I have had to service the carburetor from my old stuart turner inboard (p55 8hp).
The float had some petrol in it (which was causing the needle valve to not shut and flooding the carby at low speeds). Try as I did, I could not locate the leak, so eventually I drilled a tiny hole in the top and drained out the petrol.
Next it came to soldering up the hole and this is where I met with problems.

My girlfreind is a silversmith so we went through the normal motions that she would follow for soldering something like this.
I fluxed it and used some of her 'easiest' solder. However the original solder on the float melts at a very low temperature and began to blister before I could get the new solder anywhere near hot enough.
I have started making a bit of a mess of it, and am hesitant to try anymore (at least untill I can find some very low temp solder- any suggestions?).

I am going to ask another jewler freind who is very technically skilled and see if he has any solutions.

failing this I am wondering if I could simply epoxy up the hole I have drilled and the now suspicious seams that I have created (where the original hairline leak no doubt is).
The question
Is epoxy going to be stable in petrol?
I seem to remember people making tanks out of epoxy, but these may have just been for water.
If it is stable in petrol, will I be able to get a sufficient bond/seal to the brass?

This may be a simple matter of finding the right low temp solder.
But my girlfriend seems to think that we are using the right solder for brass.

Any suggestions?

[harhhnt]

Why Not Try A Closed Cell Foam, Injected Into The Old Housing, Available At Any Hardware Store?

[hansp77]

it is a very sensitive float- thus it would not bear well the extra weight. The problem i am trying to fix is that the carby was flooding because it was weighed down with a tiny bit of petrol and thus would never properly shut the needle valve.
Thanks anyway.

[MikeJohns]

Solder it, but not with a torch, you are using too much heat.

Sand the brass with emery paper until it is clean then use electrical resin cored solder and a 40 watt soldering iron with a flat on the tip (not a needle tip) melt a blob of solder wire onto the tip (it will stick there when melted) then introduce this to the seam hold the iron on for a few seconds you'll see the brass change colour in a circle around the tip.
Now introduce the solder to the brass close to the iron and it sould flow, you can "scrub" it on witht the iron tip to get the initial "stick" but it must result in a decent flowed joint.

Epoxy will fail.

[hansp77]

Thanks Mike,

if I read this before I did what I have just done I would have followed your advice. As it stands I managed to do it with a torch- I made a bloody mess of it, leaving myself with a lot of cleaning up to do, but as you say I got some of that electrical solder (this stuff was 'acid' cored?).
Either way, having resoldered every join it is now sealed, and though a little worse for the wear compared to its previous condition, I have tested it by weighting it down in a jar of petrol and it appears to be leak free. It has also come up a little lighter than the 33 grams that is stamped onto it (probably from my filing and sanding?) which for this enging is actually quite a good thing.

lovely made and simple thing this 60+year old carby- they certainly don't make em like they used to.
I simply have to post a couple of photos of its gleaming cast brass old-style beauty:cool:
here they are.
Now all I have to do is polish up and repaint the rest of the engine (with its extensive solid brass) to match.

[harhhnt]

The Foam Does Not Add Weight, It Fills The Chamber With Air, Keeping The Petrol From Entering And Adding Weight. Epoxey To The Exterior Would Add Weight. Closed Cell Foam Is Buoyant

[hansp77]

Thanks harhhnt, again,
I have already solved the problem.
I was always going to aim for the solder, but just wanted to know that if it failed, would epoxy be an option.

about the foam thing,

imagine if you got a lump of this closed cell foam and then put it on a set of digital scales. It is going to weigh something.
You have a heap of air, which wheighs something itself, but is equalised out (if unpressurised) because the air outside the foam weighs exactly the same.
Then you have the substance that actually makes up the cells in the foam. Whatever this is, it is heavier than air. Thus it adds wheight.

with the epoxy option (if it was actually stable in petrol) what would happen would be that a very minute amount of epoxy would seal the minute hole in the float and litterally create one big closed cell of air inside. Compared to filling the air inside the float with foam it would weigh a whole lot less.

just remember, when you look at a peice of closed cell foam floating on water, it is also sinking right to the bottom of the air.

[yokebutt]

I doubt the hardware store type foam would stand up to gasoline.

[Man Overboard]

harhant
Gravity acts on anything that has mass. That means both foam and air would add weight to the float.