'64 GF 90 Fuel Filter

[Gregory G.]

We all discussed the notches or grooves were not on the original production pieces,but what finish were the nuts on the filter ends,Cad,Chrome,Zinc plated?

Greg

[Joe L.]

Re: '64 GF 90 Fuel Filter

Greg----

It was cadmium or zinc. I don't know which. I never performed spectrophotometric analysis on the finish material.

[John D.]

Re: '64 GF 90 Fuel Filter

Greg, The old original replacement filter ends ALL appear to be cadmium. As the years went by the last batch appeared to be shiner and they were zinc. I am trying to make a decision as to what filter will go on my 63 shortly. There is so much hype about the notches on filters. Not much a car owner can do about it but keep getting dinged at the shows. The first replacment ones made in the 60's had such a slight notch that you have to get up close to stare at it. As the years progressed the notches got deeper and deeper. The last ones stood out in the crowd. There is a repro in the works but it too has notches. Such a trivial thing in the long run but it's to the point that every car will get hit for notches unless you use a fake repro. What is more correct on a restoration. A NOS repro with a hint of a notch or an expensive fake repro with no notches. If it were your car which filter would you use? That's the question of the day.
Sme say use an old original with no notches but who wants to get dirt in their fuel system from a piece of crap just because it has no notches.Sorry about venting. Thanks very much, John

[Joe L.]

Re: '64 GF 90 Fuel Filter

John-----

I think that this widely held belief that cadmium plating is "dullish" wheras zinc plating is "shiny" is inaccurate. For many years I worked in environmental regulation. I got to know a LOT of platers, both ihose that operated in the City I worked for and elsewhere. I discussed this issue with several of them. All said that there was really no way to tell cadmium from zinc by the way it appears. Cadmium or zinc could be plated with a "dullish" finish or with a "shiny" finish depending upon the customer's desires and/or standard practices of the shop (assuming the customer doesn't care which is how it is in many cases).

They said that straight out of the plating bath it MAY be possible to discern cadmium from zinc. However, after a short period of oxidation from exposure to air, the subtle difference disappears.

I had one of them do work for me on several occasions. I asked them to do certain parts in cadmium and certain parts in zinc. I asked for a "dullish" finish on both. I could see absolutely no definitive difference in the finished parts.

The platers explained to me that for many years the only real market for cadmium-plated parts were those that had to be done to a military specification. Very few parts fall into that category.

[John D.]

Re: '64 GF 90 Fuel Filter

HI Joe, Appreciate you answer on the cad vs zinc plating but I don't agree with your platers explanation. I worked in a plating shop in my younger years #1. and #2 I have a ton of parts cadmium plated about once a month. In PA there are very few cad platers so I get my plating done in Ohio. The zinc plating typically has a bluish cast to it. Yes they can leave off the last step but the zinc dulls quite quickly and then turns dark grey. For your plater to say that cadmium and zinc can be quite close is nice to here. But I tried that with my plater and it just didn't work. You are correct for sure when you describe the brite vs dull finish. Sometimes the cad is dull and sometimes it is bright. Depends on how much brightner is put in the chemicals. Get a batch that is done in the morning and it's bright. Consistency is difficult. But I dare say that I for one would able to pick out zinc plating over cadmium. But if you couldn't or I could not pick it out today we would be able to see the difference in a short period of time. The cadmium plating is more durable than the zinc. Wish what your plater said is true and hopefully it is but it's not that way with my plater. His zinc looks like zinc. Artifical and bluish. Now another plating to consider is tin. I used to get parts plated for free 30 years ago at a local industry (can't mention the name) for the old FI's and it was tin. It looked quite nice and the price was right (free). John

[Joe L.]

Re: '64 GF 90 Fuel Filter

John-----

It is true that the zinc plated parts, when freshly plated, have a very slight "bluish" hue to them whereas the cadmium have no colored hue or a very slightly "yellowish" hue. However, this usually doesn't last too long. As soon as the slightest oxidation sets in, it seems to go away. As I say, the parts that I had plated in zinc and cadmium looked almost identical. In fact, if there was any difference, at all, the zinc came closer to the original "look" I was trying to get to. I actually regretted that I had any done in cadmium.

Most of the GM plated parts specs from the 60's onward specified "zinc or cadmium finish". The only reason that I could see that a plater, given the option, would have used cadmium would be if that was what they were mostly running for other jobs. Many GM parts specified ONLY zinc. I can't say what was done earlier (50's and before). Perhaps, cadmium was widely specified then.

Many years ago, since I had the means at my disposal, I decided to check to see just how many of these "cadmium" plated parts were actually cadmium. It so happens that our laboratory had an atomic absorbtion spectrophotometer and, later, an inductively coupled plasma spectrophotometer. So, I could easily take a tiny scraping from a plated part and relatively quickly test it to see if the finish was primarily cadmium or primarily zinc (either finish is going to have other metals, including each other, in it, but I was after the PRIMARY metal in the plating). I assembled a host of original brackets, bolts, nuts, etc. and took a tiny scraping, digested in HCl and analyzed it. Guess what? Virtually every piece I tested was plated with zinc. Now, of course, I did not test every piece there ever was on a Corvette that was plated with either zinc or cadmium---just a RANDOM sampling. However, the sampling demonstrated to me that most of what was regarded as "cadmium" was actually zinc.

[John D.]

Re: '64 GF 90 Fuel Filter

Joe, My cad plater has a contract with a government agency that specifies cadmium plating. The plater is under strict guidelines to adhere to. That's basically why he does cadmium. If you are having problems in your area with a plater that is giving you a cad look a like and want the real thing let me know. It won't be too long I imagine that cadmium may be a thing of the past just like our favorite paint. Then we can get buy and use zinc and omit the last step that gives it the blue hue. But it doesn't hold up long. Once I did a fuel injection in "blue" zinc because that was what the owner specified and it looked like a clear coat paint job on an old Corvette. I couldn't wait to get the unit our of the shop. But the owner loved it so I guess that is all that counts. Actually on the mid year units Rochester Products used both zinc and cadmium on the steel parts. I hear more hype about the plating of say split lock washers on the FI's. The specs that I have buried said blackened, cadmium, or zinc. Thanks, John D.

[Richard T.]

Re: '64 GF 90 Fuel Filter

John,
I have an NOS GF-90 that was included in a Delco Fuel Filter Adaptor Kit #7017219 that I bought some years ago still in it's old orange black and white box. It includes two brass fittings for the fuel meter and the GF-90 which has the tiniest notches I've ever seen. I've never seen a filter without any notches though. Rich #2267

[John D.]

Re: '64 GF 90 Fuel Filter

Hi Rich, How have you been? I have the same filter as yours. Really tiny notches that you have to look close to see. Manilla bag with two fittings like it was a kit for a '62 FI car. I am tempted to put it on the '63 as it is as correct as you are going to get. See you in Carlisle. Thanks, John

[Joe L.]

Re: '64 GF 90 Fuel Filter

John------

I'm quite sure that the cad plating I had done was the real thing. I tested it, too. Plus, I know, for sure, that this plater did cadmium-----we saw over-limit concentrations in their wastewater all-too-often.