Using Nitric acid to dissolve Brass

[Fishnbiker]

Greetings from another Newbie. My interest here is not strictly about precious metals, but brass. After viewing a few videos on Youtube, I thought to inquire here about using Nitric acid to dissolve brass. The reason for this is hopefully to dissolve/remove a broken fuel jet needle in a carburettor needing rebuild. The theory sound easy enough (with regard to dangerous chemicals use), but there are a few questions as to access to a small amount, 20cc/one ounce to use with an eyedropper or syringe type tool for application into the hole the needle is stuck in. I understand the need for extreme care & use. I have used various solutions for other work such as electro-plating & etching. I have (I believe) the proper safety equipment. So, a few real questions;

#1 Is it available in Canada at 67% in small quantities ~ 10-20 cc ?
#2 The carb looks to be a zinc compound. Anyone know for sure if it might be safe on that metal ?
#3 What material could be used for a working bath to let the part soak? A particular metal / plastic / glass ?
#4 Disposal of unused solution ?
#5 Type of filter needed for a face mask ?
#6 Anything I may have missed ?

Thanks, Ken/Fishnbiker

 

[goldshark]

For $15, you would be better off buying a Chinese knock off carb. Unless you are a total glutton for punishment. What does it go to? Nitric is ok with Al, never seen a carb made entirely of Zinc, usually pot metal.

 

[4metals]

The reason for this is hopefully to dissolve/remove a broken fuel jet needle in a carburettor needing rebuild.

Considering you are not even sure if the needle is brass and you do not know for sure what the body of the carburetor is made of, I would say you are already in over your head.

It would be very easy to ruin the needle and the carburetor all in one shot.

 

[Thomacus]

You would be better off drilling out and use an extractor bit.

 

[Shark]

Disassemble the carburetor and give the body and valve a hard boil in water. Let it boil for at least ten minutes. Remove it from the boiling water and the needle should come out fairly easy. Use an air hose if needed to give it some pressure from the back side but don’t over do it as they pop out quite suddenly and with some force.

 

[Fishnbiker]

For $15, you would be better off buying a Chinese knock off carb. Unless you are a total glutton for punishment. What does it go to? Nitric is ok with Al, never seen a carb made entirely of Zinc, usually pot metal.

Thanks for the quick reply. The carb in question is a high performance model added to My Suzuki DR650 upgraded to 790cc. The Chinese knock offs you suggested have been discussed on a thread in great detail & have proven unsuitable for my purpose. Poor castings & sloppy fits. Seems like a waste to toss a $400+ part for a couple millimetres of metal in the wrong place.

So then, what do we know about finding something to do the job with availability in Canada? And any special concern about the process? I have plenty of time & I actually enjoy tinkering at weird jobs.

Thanks,
Ken/Fishnbiker

 

[Fishnbiker]

You would be better off drilling out and use an extractor bit.

The drill size is less than 1/32” & wedged in. Not likely workable.

 

[Fishnbiker]

Disassemble the carburetor and give the body and valve a hard boil in water. Let it boil for at least ten minutes. Remove it from the boiling water and the needle should come out fairly easy. Use an air hose if needed to give it some pressure from the back side but don’t over do it as they pop out quite suddenly and with some force.

Will see about that tomorrow.

 

[Thomacus]

You have a new needle size it up with the drill bit go one size smaller and tap it out with the same size threads.

 

[Thomacus]

You are going from 650 to 790 you will have to re jet the carb Eney way.

 

[goldshark]

Will see about that tomorrow.

Are we talking about a jet, or a broken needle/seat?

 

[goldshark]

Also wanted to add- don't use ethanol gas in a carb, injection only. The Ethanol turns to a Karo syrup like substance, which gums up moving parts.

 

[Yggdrasil]

Also wanted to add- don't use ethanol gas in a carb, injection only. The Ethanol turns to a Karo syrup like substance, which gums up moving parts.

Strange, the ethanol itself should not do that.
And the heat and parts in the injectors should just as easily gum up.
I believe it must be dissolved gaskets, seals and other rubber that cause it.
If you run an "older" car they most certainly need to be "upgraded" to tolerate the new fuel.
Same story about older diesels and biodiesel.

 

[snail]

I believe the issue is when the alcohol cosolvent evaporates in the carburetor bowl it leaves behind water soluble compounds that were held in suspention by the alcohol.

 

[Fishnbiker]

Considering you are not even sure if the needle is brass and you do not know for sure what the body of the carburetor is made of, I would say you are already in over your head.

It would be very easy to ruin the needle and the carburetor all in one shot.

The needle is definitely brass. I have seen this dissolving processor on several Youtube sites from different sources & even as I am not familiar with the exact composition of the carb body, I have seen it not affected. I have nothing to lose & everything to gain on the concept, being as I have the OEM carb to fall back on. This performance carb is useless as is.

Strange, the ethanol itself should not do that.
And the heat and parts in the injectors should just as easily gum up.
I believe it must be dissolved gaskets, seals and other rubber that cause it.
If you run an "older" car they most certainly need to be "upgraded" to tolerate the new fuel.
Same story about older diesels and biodiesel.

All this is well under control. I only discovered the broken needle tip during the cleaning process. I clean my carbs every winter after it is drained, so that is never a problem. No injectors & not a car.

The offending part was broken off the screw & is physically jammed in its jet & too small for any mechanical removal techniques. It is only 4mm long & the whole new needle is 36mm.

My main concern in asking was more directed to availability of the HNO3 in Canada, materials for a drip tray or dip pot, its resistance to the acid, & safety in use.

Thanks, Ken/Fishnbiker

Thanks,
Ken/Fishnbiker

 

[Fishnbiker]

Are we talking about a jet, or a broken needle/seat?

Broken needle stuck in the jet. Broken needle left hand side, new one on the right. The needle tip is 4mm, the total part is 36mm.

 

[Fishnbiker]

Broken needle stuck in the jet. Broken needle left hand side, new one on the right. The needle tip is 4mm, the total part is 36mm.

 

[grainsofgold]

worst case buy 14karat test acid

 

[Fishnbiker]

worst case buy 14karat test acid

Can anyone tell me the colour of the nitric acid as seen on samples of Amazon offerings? I see lots of clear & a few of brownish yellow & none (so far) that give their true formulas. Some are alleged to work on silver as well. Same chemical?

Thanks,
Ken/Fishnbiker

 

[kurtak]

#2 The carb looks to be a zinc compound.

If the carb is made of "die cast" (which is primarily zinc) nitric will destroy the carb as nitric reacts with zinc

If the carb is made of cast aluminum the nitric will have little or NO effect on the carb as nitric does not react with aluminum

So if it was me - I would test the outside of the carb body with a drop or 2 of nitric to see how it reacts - before using the nitric on the inside of the carb

Also - if you are using 67 - 68% nitric you first need to dilute the nitric 50/50 nitric/distilled water to dissolve the brass --- do not use tap water to dilute the nitric as the chlorine in tap water will make a week AR and AR will react with both zinc & aluminum

Kurt