Valve cover color?

Discussion in '206/246' started by James lafevers, Apr 27, 2019.

  1. synchro

    synchro F1 Veteran

    Feb 14, 2005
    Full Name:
    #26 synchro, Apr 30, 2019
    Last edited: Apr 30, 2019
    I think yours looks about as badly corroded as my valve covers were on 05082. I had that white stuff (efflorescence?) creeping up in sections too.

    Here I place a freshly glass bead tumbled valve cover from Dino 05702 USA (top) next to a well used, corroded valve cover from 05082 EU-Italy about to be sent to Ollies in Havasu City for glass bead tumbling.
    That last photo shows the same casting now clean with amazing luster.
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  2. carguy246

    carguy246 Formula Junior
    Silver Subscribed

    Nov 8, 2006
    Yes, that is what I was trying to describe. Tumbled cover looks new.
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  3. Motob

    Motob Formula 3
    Professional Ferrari Technician

    Nov 11, 2003
    Berkeley, CA
    Full Name:
    Brian Brown
    It may look "new" to you, but that is not what the early mag cam covers looked like when the cars were new. They were a dark grey finish, of which is apparently from the Dow7 process. Now the cover has no protection from corrosion.
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  4. synchro

    synchro F1 Veteran

    Feb 14, 2005
    Full Name:
    I hit it with a light coating of rattle-can clear matte, but you're right it is exposed.
    Then again, it took 10 yrs of my ownership to age that way and I put more km on that Dino than all prior owners combined, so perhaps it will be OK for a few years.

    What are you using on Cam covers since Dow7 is discontinued ? I saw Matthias' restoration cam covers and they look painted, perhaps the only way to replicate?

    Forgot to mention, the USA cam covers on 05702 are heavier than the EU-Italy mag alloy ones on 05082.
    Some of our Dino castings are absolutely gorgeous pieces of art.
  5. rosemeyer

    rosemeyer Karting

    Aug 13, 2010
    As others have mentioned on this thread, the 206 and early 246 cam covers ( as well as the oil filler neck, the cam end caps and the distributor spacer) were magnesium and were treated with DOW7. Like Cadmium plating which is now harder to get but not yet extinct, DOW7 is still out there.

    Last year I attended a trade show and stumbled on a small booth that was filled top to bottom with DOW7 plated mag parts. The exhibitor was a low run producer of parts in specialty alloys, including magnesium. They struck me as very competent in my brief chat with them. For those interested, here is their name. Perhaps they'd be willing to include some Dino parts in one of their runs?

    Lite Metals Company (

    A note that the final finish depends on a myriad of factors including the age and condition of the parts themselves. Don't be surprised by considerable variances in the finished product. Trying to match an 'ideal' colour is a recipe for frustration and a sure fire way of being kicked out of the plating shop :)

    Best Regards,
  6. racerboy9

    racerboy9 Formula 3
    Silver Subscribed

    Nov 3, 2003
    I strive for originality but sometimes you have to punt. If it were me and my cam covers were too far gone to be presentable, I would find the color that you think is closest/correct for the Dow7 coating and refinish them with zinc chromate primer and then the color coat. Baking the parts after a few days can achieve a finish almost as durable as powder coating.
  7. DinoLasse

    DinoLasse Formula Junior
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    May 26, 2009
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    Paul (rosemeyer) is absolutely right: The Dow 7 chemicals are out there and available, and at least some platers appear to be doing the process. Here is source for the chemicals, for example:

    And here is a plater who lists the Type III (Dow7) for magnesium passivation on their web site. And in Anaheim, in environmentally concious California, of all places! I don´t know if I misread their info or if it is an old web page, but it may be worth giving them a call:

    I did a lot of searching on this subject because I plan to do my valve covers and other magnesium parts later on. Here in Sweden only two platers do magnesium passivation and they both use the yellow type which would look completely wrong. I will consider sending them to the US if it can be done there.

    If anyone finds success with this or any other plater, I hope you will post the results here.
  8. rossnzwpi

    rossnzwpi Rookie

    Jan 15, 2010
    Regarding the Magnesium cam covers (not to be confused with the aluminium ones on 246 and later cars, which are bare metal) - they need to be passivated through the DOW process or will corrode, even under paint. Aluminium corrodes to create a hard layer of oxidation that actually protects the metal, thus they can be left bare of blasted with an aggressive material, then left to corrode slightly and remain in that state.

    Magnesium must be protected and the more magnesium in the alloy the more important it is. Cromodora wheels and Dino engine parts were not the same alloy and therefore were treated with different versions of the Dow process. The Dow process creates a variety of colours depending on variables such as the length of time left in the bath, temperature, atmosphere and alloy. It is always a dull brown/orange/gold and even green. The wheels, especially have a green cast. Originally the Dow system was not meant to be the only long term coating but it seems Ferrari and Fiat did not apply any other coats to engine parts - although Cromodora did then paint the wheels. Many people have since added black or gold (to match the brochures set-dressed photos, which show all the magnesium components as bright shiny gold). Just Dow does not hold up well to salt water exposure or even water.

    WD40, like any oil will help with corrosion but it is not recommended because it acts as a water attractant to draw moisture from the surface IN THE SHORT TERM but actually holds onto the water long term and is therefore problematic.

    Dow is out of the business of hexavalent chrome magnesium treatments these days and many repair shops avoid the highly toxic process too. I'm looking at preserving my mag parts now, perhaps with Henkell's version of Dow or with the modern Pantheon Chemical's PreKote (which is non-toxic and used on aircraft magnesium parts). PreKote however will need to be painted. Here's a picture of my two early FIAT Dino cam covers - one as is, showing the golden Dow finish overlaid with a thin layer of black that is virtually worn away. The other is mag that has been wire-brushed of nearly all its Dow. You can see how pitted and corroded it is!
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  9. rossnzwpi

    rossnzwpi Rookie

    Jan 15, 2010
    My guess is that Dow 7 was used on Dino engine parts and Dow 17 on wheels (Dow 19 can be used for touch ups). As PTI industries say (

    Dow 7 (Chemical conversion coating) is a good choice for both new and overhauled parts that have dissimilar materials such as inserts, or where conditions will tolerate a less robust and less costly alternative to Dow 17. Dow 7 is a chemical conversion coating which results in no appreciable dimensional change to the component. The surface of components coated with Dow 7 is changed to a brassy or dark brown finish depending upon the alloy. PTI can forward parts to local vendors for painting as well, saving our clients time and lowering shipping expenses.

    Dow 17 (magnesium anodize) is an anodic process that imparts a hard, corrosion resistant coating to all magnesium components regardless of alloy. The Dow 17 process results in a green or dark green surface finish that varies with alloy. After the Dow 17 process, the parts resistance to corrosive elements and abrasion are greatly improved and the surface is now ready for post-treatments including painting.

    Dow 19 (Chromic acid coating) Chromic acid, also known as Dow 19, is a treatment that is used on magnesium parts that need a spot touch-up to repair minor damage or a temporary coating to prevent corrosion between production processes. Parts can be coated with Dow 19 by manual application or by immersion in a tank of Chromic Acid. After Dow 19 coating, parts appear to be a brassy brown color but can vary slightly depending of the alloy. There is no appreciable dimensional change to the component from the Chromic Acid process.
  10. rossnzwpi

    rossnzwpi Rookie

    Jan 15, 2010
    The chemicals used to prep the magnesium die cast alloy contain hydrofluoric acid which, according to chemical supermarket are:

    "**This is the most dangerous industrial acid in existence**
    Attacks calcium in bones. Strong irritant to eyes and skin. Highly corrosive to skin and mucous membranes. Toxic by inhalation and ingestion. Will attack glass specifically and generally any silicon-containing materials."

    No wonder it is banned in lots of places! I'm very inclined to use the PreKote non-toxic prep and paint it afterwards. Ids Berma does Dino engines and paints the cam covers to look like they are passivated. I think the matte finish and semi transparency of Dow 7 is pretty hard to achieve though.
  11. FredF

    FredF Rookie

    Sep 16, 2005
    Hampton Bays NY
    Full Name:
    Fred F
    I had mine treated with DOW7 then powder coated with a satan black. Below is the result of the DOW7.

  12. pshoejberg

    pshoejberg Formula 3
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    Dec 22, 2007
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    Peter H
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  13. rossnzwpi

    rossnzwpi Rookie

    Jan 15, 2010
    Great work Fred. I'm about to do this to my 2 litre engine but am considering the non-toxic PreKote, followed by painting. Then of course comes the decision of what colour to paint it! Perhaps a matte finish approximating raw magnesium. Your black is a good choice and my cam covers appear to have an almost worn-off layer of black over the bronze-like Dow colour. It is interesting that in your "before" picture there doesn't seem to be any Dow 7 colouration.

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