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PostPosted: Fri Jan 04, 2019 11:00 pm 
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Location: San Diego, California
I bought a set of Super 90 heads at the Phoenix Club swap meet last year.
I would like to restore them in their original black color.
What is the proper way to do it ?

Thanks !

Pascal Giai


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PostPosted: Fri Jan 04, 2019 11:17 pm 
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I've seen some fellows use this on brake calipers (they look great) but I think a conversation with the tech guys at the manufacturer would be in order to see if this application would be appropriate-- https://www.cerakote.com/finishes/


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PostPosted: Sat Jan 05, 2019 11:52 pm 
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Years ago I used Hi-Temp exhaust paint on a set of S90 heads, and I assume they'er still out there--somewhere.
The heads must be really pressure-cleaned off and masked for non-colored areas. The original S90 cylinders were
also 'blackened', but it didn't really do much for dissipation of heat and it wasn't continued on later sets of P/Cs.


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PostPosted: Sun Jan 06, 2019 12:28 am 
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I had one 'original' C many years back (electric tach, so I assume a 1964 build at earliest), and I really can't claim it was original. But on rebuilding the engine, nothing suggested any major parts had been replaced for those provided by the factory, and it had blackened heads. Those heads did not have S90 valves.
I talked with EASY Jim and Stable Alan at the time; neither could shed any light on the matter. The engine got rebuilt and who knows who owns it now.
Like all Cs, it was a wonderful street engine; I cannot say it ran cooler than others and I had not the knowledge to test the upper limit of the CR at the time (nor even a reliable way to calculate it).

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PostPosted: Sun Jan 06, 2019 2:25 am 
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I just looked at one of mine, they are anodized black. Mine looks like it was done before they were machined. The combustion chambers are aluminum but the rest of the metal is black, the coating is only a couple mills thick.

https://www.anoplate.com/finishes/anodizing/

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PostPosted: Sun Jan 06, 2019 9:03 am 
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Yes; every early original C engine I have dismantled had black heads. I don't remember any SC heads, so can't report whether they were black also, but I would assume so. Since the heads were IDENTICAL on C and SC, except for the exhaust valves, I presume all the C/SC heads were blackened early on.

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PostPosted: Sun Jan 06, 2019 10:02 am 
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Were they anodized or something more paint-like?

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PostPosted: Sun Jan 06, 2019 10:23 am 
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Judging by the ease of removal when bead-blasting, I assume not anodizing. Don't know the exact process.

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PostPosted: Sun Jan 06, 2019 10:30 am 
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Ditto on John's and Vic's comments. I'm putting an early C motor #710070 in my Beck Spyder. The black heads were definitely not painted but instead anodized before machining. I soda blasted and solvent cleaned them and the finish came out nearly good as new. Paint wouldn't have survived the years or the cleaning. Have you cleaned yours up yet Pascal? If not, they may look better than you think.

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PostPosted: Sun Jan 06, 2019 10:33 am 
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OK, it looks now like Vic and I are at odds on it.

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'60 356B (Ivory cab)
'63 356B (Ruby Red coupe)
'67 912 (Rally car)
'68 912 (Golden Green)
'70 911T (Bahia Red)
'14 911-50th (GTS)
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PostPosted: Sun Jan 06, 2019 11:05 am 
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Bruce; I won't argue. I haven't used soda blasting, so my glass-bead blasting was probably too aggressive.

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PostPosted: Sun Jan 06, 2019 12:29 pm 
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The factory machined after blackening so it would have been tough to keep paint intact. Zenith throttle bases were also blackened before machining. These are iron so would have been Parkerized not anodized. Same idea, different purpose. Just my opinion.

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Bruce

'60 356B (Ivory cab)
'63 356B (Ruby Red coupe)
'67 912 (Rally car)
'68 912 (Golden Green)
'70 911T (Bahia Red)
'14 911-50th (GTS)
'18 Beck 550 Spyder (356C motor)
'62 Austin Mini (850 stock)


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PostPosted: Sun Jan 06, 2019 1:54 pm 
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How would blackening lower temps or was there another reason for blackening?

Mike

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PostPosted: Sun Jan 06, 2019 2:04 pm 
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In thermodynamics, a black body radiates heat better; or something. Also why polishing your brake drums is a bad idea. The original rougher surface radiates heat better. In practice, it's probably negligible, depending on the part.

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PostPosted: Sun Jan 06, 2019 2:14 pm 
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Vic Skirmants wrote:
[...]In practice, it's probably negligible, depending on the part.

As evidence, you just need to look at the remaining IC aero engines; those are not cost-sensitive (shall we say), the mfgrs want to cool them as much as they can to improve C/R (and performance), and none of them blackens any parts that I know of.
We need Mike Horten to pipe up here.

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