How to "blacken" Super 90 Heads ?

356 Porsche-related discussions and questions.
Message
Author
User avatar
Pascal Giai
356 Fan
Posts: 165
Joined: Thu Jul 03, 2008 7:25 pm
Location: California

How to "blacken" Super 90 Heads ?

#1 Post by Pascal Giai »

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

User avatar
Jim Nelson
356 Fan
Posts: 2138
Joined: Wed Mar 26, 2008 2:18 pm
Location: SoCal

Re: How to "blacken" Super 90 Heads ?

#2 Post by Jim Nelson »

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/

Dick Weiss
356 Fan
Posts: 4181
Joined: Sun Apr 20, 2008 12:54 am

Re: How to "blacken" Super 90 Heads ?

#3 Post by Dick Weiss »

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.

User avatar
Ron LaDow
356 Fan
Posts: 8092
Joined: Wed Mar 26, 2008 11:45 am
Location: San Francisco

Re: How to "blacken" Super 90 Heads ?

#4 Post by Ron LaDow »

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).
Ron LaDow
www.precisionmatters.biz

User avatar
John Brooks
356 Fan
Posts: 2146
Joined: Tue Jul 08, 2008 11:50 am
Location: Whidbey Island WA.
Contact:

Re: How to "blacken" Super 90 Heads ?

#5 Post by John Brooks »

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/
John Brooks

62 Roadster
66 912
84 Cab
getting pushed around in porsches since 1965

User avatar
Vic Skirmants
Registry Hall of Fame
Posts: 9279
Joined: Tue Oct 27, 2009 5:02 pm
Location: SE Michigan
Contact:

Re: How to "blacken" Super 90 Heads ?

#6 Post by Vic Skirmants »

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.

User avatar
Martin Benade
356 Fan
Posts: 12181
Joined: Wed Nov 23, 2011 10:52 am
Location: Cleveland, Ohio

Re: How to "blacken" Super 90 Heads ?

#7 Post by Martin Benade »

Were they anodized or something more paint-like?
Cleveland Ohio
62 Cabriolet
56 VW
02 IS 300
04 Sienna

User avatar
Vic Skirmants
Registry Hall of Fame
Posts: 9279
Joined: Tue Oct 27, 2009 5:02 pm
Location: SE Michigan
Contact:

Re: How to "blacken" Super 90 Heads ?

#8 Post by Vic Skirmants »

Judging by the ease of removal when bead-blasting, I assume not anodizing. Don't know the exact process.

User avatar
Bruce Smith
356 Fan
Posts: 1624
Joined: Sun Jun 19, 2011 9:47 am
Location: Rochester, NY
Contact:

Re: How to "blacken" Super 90 Heads ?

#9 Post by Bruce Smith »

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.
Bruce Smith

User avatar
Bruce Smith
356 Fan
Posts: 1624
Joined: Sun Jun 19, 2011 9:47 am
Location: Rochester, NY
Contact:

Re: How to "blacken" Super 90 Heads ?

#10 Post by Bruce Smith »

OK, it looks now like Vic and I are at odds on it.
Bruce Smith

User avatar
Vic Skirmants
Registry Hall of Fame
Posts: 9279
Joined: Tue Oct 27, 2009 5:02 pm
Location: SE Michigan
Contact:

Re: How to "blacken" Super 90 Heads ?

#11 Post by Vic Skirmants »

Bruce; I won't argue. I haven't used soda blasting, so my glass-bead blasting was probably too aggressive.

User avatar
Bruce Smith
356 Fan
Posts: 1624
Joined: Sun Jun 19, 2011 9:47 am
Location: Rochester, NY
Contact:

Re: How to "blacken" Super 90 Heads ?

#12 Post by Bruce Smith »

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.
Bruce Smith

User avatar
Mike Wilson
Classifieds Monitor
Posts: 11490
Joined: Tue Apr 15, 2008 4:37 pm
Location: SW Los Angeles

Re: How to "blacken" Super 90 Heads ?

#13 Post by Mike Wilson »

How would blackening lower temps or was there another reason for blackening?

Mike
Mike Wilson
Lomita, CA
'63 B coupe

User avatar
Vic Skirmants
Registry Hall of Fame
Posts: 9279
Joined: Tue Oct 27, 2009 5:02 pm
Location: SE Michigan
Contact:

Re: How to "blacken" Super 90 Heads ?

#14 Post by Vic Skirmants »

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.

User avatar
Ron LaDow
356 Fan
Posts: 8092
Joined: Wed Mar 26, 2008 11:45 am
Location: San Francisco

Re: How to "blacken" Super 90 Heads ?

#15 Post by Ron LaDow »

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.
Ron LaDow
www.precisionmatters.biz

Post Reply