Carb Casting Repair, Zinc Solder?
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Carb Casting Repair, Zinc Solder?
I am looking to fill a hole in a carb casting. OK I know it is zinc and where this gets a little dicey, I want it to be undetectable. I will metal finish it and then chromate the casting to get back to the original color. Some aluminum alloy will not work. I am looking for some sort of low temperature zinc (primarily 80% or better) rod to braze with. Thoughts?
Re: Carb Casting Repair, Zinc Solder?
Maybe call Sean at SMI in huntigton beach CA of what to use?Tom
Re: Carb Casting Repair, Zinc Solder?
Probably better off contacting a panel shop that restores older cars that used zinc castings for emblems, tail light housings etc.
Re: Carb Casting Repair, Zinc Solder?
Why not use a 2 part epoxy , simple to use and will last forever. JMOHDBD wrote: ↑Fri Apr 23, 2021 11:11 am I am looking to fill a hole in a carb casting. OK I know it is zinc and where this gets a little dicey, I want it to be undetectable. I will metal finish it and then chromate the casting to get back to the original color. Some aluminum alloy will not work. I am looking for some sort of low temperature zinc (primarily 80% or better) rod to braze with. Thoughts?
Re: Carb Casting Repair, Zinc Solder?
Fixing is one part of the issue. this is a valuable rare casting and I need to then restore the original dichromate gold look for authenticity reasons
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Re: Carb Casting Repair, Zinc Solder?
I have made repairs with the rods they sell for fixing pot metal to make about a square inch of fuel bowl bottom ,used some rusty metal to make a form for the bottom melted it in, it looked somewhat ugly but was still working 15 years later, perhaps if I had practiced some it could have been nicer looking
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Re: Carb Casting Repair, Zinc Solder?
I would ask on specialist forums that do plating. WAG that you could electroform copper to fill the hole -- polish/finish it and then plate it. You will need advice on masking, solutions, etc.
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Re: Carb Casting Repair, Zinc Solder?
HDBD, if you use zinc or pot-metal rod to weld the thing, be prepared for pinholes. Zinc is even worse to weld perfectly than cast iron- which for me is only for magicians with all their dues paid. So at some point you are gonna have to consider fillers. Grind a piece of another carb and mix the grindings with a transparent epoxy to make a filler with the right color. Some chromate coatings will bridge over small filler repairs. Good luck.
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Re: Carb Casting Repair, Zinc Solder?
If it is that important or that valuable then send it somewhere who does ZINC welding.
Years ago when engineering new carburetors Holley had people who could weld just about anything Zinc ...
I am sure there are places to do this.
Years ago when engineering new carburetors Holley had people who could weld just about anything Zinc ...
I am sure there are places to do this.
http://www.rmcompetition.com
Specialty engine building at its finest.
Specialty engine building at its finest.
Re: Carb Casting Repair, Zinc Solder?
I restore carburetors for a living, maybe I can help.
If you'd like, shoot me a PM.
Eric
If you'd like, shoot me a PM.
Eric
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Re: Carb Casting Repair, Zinc Solder?
Looks like VMC is going to be your first port of call.
As a point of interest HDBD, what make and year is the carburetor you are working on?
As a point of interest HDBD, what make and year is the carburetor you are working on?
Re: Carb Casting Repair, Zinc Solder?
Bringing this to the top.
Working on a Holley list 3124 dated 1965 L78 396 carb . Choke housing got hit and bent, small piece is cracked at the top.
I have found 99% pure zinc solder and successfully got it to bond with the base metal experimenting with a scrap core. The base metal needs to be molton and a very direct small flame is needed. The casting needs to be supported as it wants to fall into itself if I am not extremely careful with the heat. It takes a technique moving off when there is a sign that the casting molton area is growing. Very delicate work. I wish I could use TIG but IME striking a torch to the zinc casting just spews black impurities, even at low heat with small tungsten and cup. I also wish there was a flux I could use. Was thinking about using borax as an experiment. Not sure about the boric acid. Have used Gasflux, type FB3-K, with straight acetylene to production braze steel but couldn't justify this here as these are occasional jobs and the equipment and fluid I used is long gone plus no idea if it is compatible.
There aren't too many guys around any more that get this stuff. I have a friend, 86 now, that worked at Chevrolet on the original Corvette Ramjet cars. He is an expert. Sure would like to find an expert to fix these castings. I am a little gun-shy to dive in, to be honest.
Working on a Holley list 3124 dated 1965 L78 396 carb . Choke housing got hit and bent, small piece is cracked at the top.
I have found 99% pure zinc solder and successfully got it to bond with the base metal experimenting with a scrap core. The base metal needs to be molton and a very direct small flame is needed. The casting needs to be supported as it wants to fall into itself if I am not extremely careful with the heat. It takes a technique moving off when there is a sign that the casting molton area is growing. Very delicate work. I wish I could use TIG but IME striking a torch to the zinc casting just spews black impurities, even at low heat with small tungsten and cup. I also wish there was a flux I could use. Was thinking about using borax as an experiment. Not sure about the boric acid. Have used Gasflux, type FB3-K, with straight acetylene to production braze steel but couldn't justify this here as these are occasional jobs and the equipment and fluid I used is long gone plus no idea if it is compatible.
There aren't too many guys around any more that get this stuff. I have a friend, 86 now, that worked at Chevrolet on the original Corvette Ramjet cars. He is an expert. Sure would like to find an expert to fix these castings. I am a little gun-shy to dive in, to be honest.
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Re: Carb Casting Repair, Zinc Solder?
What are you using on the body of the carb?
The body of this carb looks like it was Zinc plated , and then chromate applied, which would not be correct. Only the steel parts would have been done this way originally. The body of the carb should be chromate only , this would be less shiny.
Re: Carb Casting Repair, Zinc Solder?
The castings weren't zinc plated, they were stripped (proprietary process) and chromated.
Re: Carb Casting Repair, Zinc Solder?
rgalajda is right, the color is too bright yellow gold for a restoration carb. OEM carbs, and particularly Fords, were a darker bronze color. I think if you add more chromate to the bath it will produce a darker color. The Caswell book refers to adjusting the color by changing the concentration of chromate.