I have a 67 327/350 with the original Holley 4160 Carb which I have rebuilt many times through the years. Recently I had to rebuild it again and I notice the gold coating is flaking off more and more. One spot inside the air horn (really it is the cavity where the power valve head would go on a 4150) has most of the coating gone and the metal under it is very powdery. I was wondering how to best fix this. It is the original air horn so I would like to keep it as it has the numbers for the model and date codes on it. Is there something I can do to recoat it or is there some service that will do it. Any information would be appreciated.
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Ray
1967 327/350 HP Coupe
(Bloomington Gold Survivor 2010)
(NCRS Top Flight Award 2010)
2005 Coupe -
Re: Coating on Carb is coming off
Charles,
The gold should be gold plating or a chemical process. Some rebuilders painted their carbs and that would indicate flaking off.
The white powder is corrosion and that needs attention. The best thing would be to tear it down and replate it or chemically treat it.
I have used alodine (gold) in the past after cleaning with brightener (a acid used to remove corrosion & prep aluminum for paint) and the alodine gave a gold finishand corrosion resistance.
I have not been able to get that finish again with alodine as I think California may have forced a chemical change in order for it to be sold here.
The prep acid removes the corrosion before the alodine is used and the reason for the gold was to be able to see where the alodine treated.
Alodine is also clear and not tinted gold.
Eric Jackson does a beautiful job on carbs and would be able to give you the best advice. I don't have his # handy but it would be easy to get here on the forum.
DOM -
Re: Coating on Carb is coming off
Charles,
The body and most parts of the Holley 3810 (which is the correct one for your 67/327) is potmetal and not aluminum. The plating process is a dichromate process (Yellow Dichromate, sometimes called gold or cadmium dichromate)
The following thread illustrates the process:
There is a Restorer Story on the full restoration of a 3810, a few years ago (I forget what issue off hand)
I only do it for a hobby with my 67, but there are guys out there that do it commerciallyJerry Fuccillo
1967 327/300 Convertible since 1968Comment
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Re: Coating on Carb is coming off
You can buy the yellow dichromate from Caswell plating and do it yourself. http://www.caswellplating.com/Comment
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Re: Coating on Carb is coming off
I have never tried the commercial DIY methods. But, I remember visiting Jon Enyart's Pony Carbs shop many times, and he would always preach about the multiple dichromate baths he used when restoring the Holleys. He said the color has to be deep set into the metal to last, and it takes time and equipment, he used to have to have the New Mexico Environment Department and the EPA inspect his dichromate operations regularly to keep his license to use it all. That is very dangerous stuff.Big Tanks In the High Mountains of New MexicoComment
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Re: Coating on Carb is coming off
My guess is that he was also doing cadmium and maybe chrome. Both involve highly toxic chemicals. I did a lot of dichromate plating when we had the restoration shop. Still able to get the plating supplies shipped with out hazmat labels. Still have the equipment and chemicals collecting dustDick WhittingtonComment
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Re: Coating on Carb is coming off
Here's the stuff I used in the carburetor thread:
It is not as hazardous as cadmium. But it does ship as hazardous like spray paint.
I dilute it with distilled water and heat it up in a plastic bucket or crockpot.
It works on both zinc and cadmium plating
On potmetal (which is mainly zinc) you don't have to zinc plate before you use it. Just prep the part to a bright shiny finish and dip it for 20-30 seconds in the heated solution.
See the thread in my post aboveJerry Fuccillo
1967 327/300 Convertible since 1968Comment
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Re: Coating on Carb is coming off
Maybe I was thinking 'bout some of the other stuff coming w/o labelsHere's the stuff I used in the carburetor thread:
It is not as hazardous as cadmium. But it does ship as hazardous like spray paint.
I dilute it with distilled water and heat it up in a plastic bucket or crockpot.
It works on both zinc and cadmium plating
On potmetal (which is mainly zinc) you don't have to zinc plate before you use it. Just prep the part to a bright shiny finish and dip it for 20-30 seconds in the heated solution.
See the thread in my post aboveDick WhittingtonComment
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Re: Coating on Carb is coming off
Dick,
Do you mean, like my grappa, or your corn stuff
Jerry Fuccillo
1967 327/300 Convertible since 1968Comment
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