Black Chromate finish for MFI throttle bodies and Solex intake manifolds

[1QuickS]

Thought the source for this finish would be appreciated by those wondering how to protect your magnesium parts. The name of the supplier is Gary Arentz and can be reached at 209.754.4496 or by email: ksagea@msn.com. Gordon Ledbetter recommended him and after talking to Gary I found out he provides magnesium chromating service for the Collier Museum.

I currently have another set of Solex 40PI intake manifolds with Gary and he believes he can replicate the OEM finish of the early Solex manifolds, I'll post the results when they are finished it it works out well. I also have another source for the early magnesium finish but this is developing.

The pictures show first the MFI throttle body (assembled but not quite finished) and a NOS MFI body in the background (dirty but NEVER installed). The finish is perfect to that of the original.

The second picture is of the Solex manifold with completed carbs installed, for my money I think it looks rather nice and somewhat better than my own version of metal prep with Gibbs.

[304065]

Paul,

The MFI TB looks GREAT! What is the substrate that the chromate conversion coating applies to, is it copper first, then black zinc?

On the Solex, well, you know my ongoing saga to replicate that (which is also the early Weber manifold finish). Given the price of Solexes these days, guys who re-work them will want the original silver finish IMHO. For the vintage racing crowd, a different story-- if I were not focused on originality I would absolutely want the maximum corrosion protection for those unobtanium manifolds.

Good for you for continuing to evolve the state of the art!

[1QuickS]

Hi John,

The black is a conversion coating applied over clean magnesium, it is not a plating finish. The phosphoric based metal etch that is commonly available doesn't come close to the black. Gary told me that when he was restoring his Lotus 79 he received the chromate formulation directly from Cosworth so he could refinish the Ford/Cosworth DFV and associated engine/transmission components.

He said he knows what I seek in the silver iridescent finish and believes it is achieved before the bath makes the part black. I also believe he has achieved this already for the Collier Museum. He is going to perform the finish on one of the manifolds I sent and send a photo for me to review. I do have another alternate path that I know will provide THE finish we seek. I do not want to divulge more but I know the answer is close at hand. I've been offered the formula/process but haven't made the decision to go for it. I work in California and there are some chemicals that are frowned on here and a small shop is even more challenged.

The black finish was selected for the Solex project as the best available until better is found, at least it shows well.

[Jim Garfield]

Those look great Paul. Does Gary Arentz use the Dow 9 process to get this finish?

[1QuickS]

No, per my discussion with Gary he uses no Dow process to achieve his finish.

[Alan.uk]

On the throttle bodies on other mag parts we also made up a solution to chromate to obtain a more grey finish. I also like the black coating very much. Just wish we were closer so we could use this service. Here is a pic of our throttle bodies in the grey finish.



And on a fan



And engine cases



Thanks
Alan