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Correct appearance of mag throttle bodies
I'm restoring my '69 Porsche 911E 2.0 Mfi. I want it to be as close to the original as possible. Body is fine, now i'm working on the optical appearance of the engine. I have some problem with the magnesium throttle bodies and stacks. On my engine they are very dirty and oxidised. By many restorations people just clean and peint them to black. But i think tehy were not painted but had some kind of greyish (maybe oxidised) finish on them. So i started to think what to do.
The first step was the disassembly and visual inspection  And then the media blasting (only the body. Flanges were not touched)  I tried to figure out how could i replicate the magnesium finish (even if i don't know how it looked like  ). I found a really cheap (less than 1USD) fine graphite powder in the paint shop. I found that the color of graphite should be close to the mag color. But how it will stick to the housing and how it won't pill? First with a brush soaked onto motor oil i just "painted" the graphite powder onto the surface and then burned it in with a propane burner (of course always checked the temperature of the housing with an infrared thermometer and didn't let it to rise above about 120Celsius).On this temperature the oil mixed with graphite powder diffused onto the mag surface and gave it a grey color. On the picture below you can see 3 color shades on the three bores. It's because it needed 3 coats to achive the desired color. The first 2 coats were too light as you can see   At the end it turned out quite good. But because i don't knwo how it exactly should look like, i need some expert's advise. Did i made something wrong? The "paint" don't come off, has a metal like finish, not painted and cost 1USD and 2 hours. The final "product". Maybe is is still too light? Should i darken it a bit? Looks a bit shiny on the pictures, but the shine is between matte and satin in the real life.  Tomorrow i'll galvanise (in my homemade galvanising corner) the bolts and other stuff with yellow passivation and assemble everything. I will post pictures of it also.
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1969 911E 2.0 restoration project in progress... Last edited by hun911; 10-06-2015 at 02:36 PM.. |
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10-06-2015, 02:31 PM
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Graphite and magnesium are highly dissimilar metals, very far apart on the galvanic corrosion chart. Mag is very anodic and graphite very cathodic. In contact with one another, the anode (magnesium) would be expected to corrode away.
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10-06-2015, 03:38 PM
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Then i should find another way...
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10-06-2015, 03:52 PM
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I send mag items to my refinisher who provides a magnesium chromate finish. He routinely provides this service for Collier's museum in Florida as well as for other well respected providers.
You can see some of his work on my Gallery web page here: Performance Oriented By the way, Nice job!
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Paul Abbott Weber service specialist www.PerformanceOriented.com Last edited by 1QuickS; 10-06-2015 at 04:18 PM.. |
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10-06-2015, 04:15 PM
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Location: Copenhagen-Denmark
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Hans / 1972T MFI coupe |
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10-07-2015, 04:27 AM
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I changed my nind because i saw a NOS '69 TB and it was painted so i chromated my TB's and then painted to flat black. Galvanised all the metal parts and made new alu rods because the old ones are bent. It needs adjusting but here is the end result without the yellow and red paint markings on the bolts
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10-20-2015, 06:54 AM
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Looks good!
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10-20-2015, 09:51 AM
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