I'm replacing my intake manifolds on my 68 911 because the bores are severely pitted. I'm trying to determine the original exterior manifold finish. Is it a natural finish or painted? Here is a pic of the old pitted manifold. I don't know if it is original or not.
Thx,
Dan
It sure looks original right down to the corroded magnesium. Somewhere along the way, Porsche started using a black epoxy finish on the manifolds which was extremely durable, such that it's hard to sandblast off even today. But we have to remember that Porsche was using carbs right up until 1973 (the Euro 2,4T motor was a T-vergaser whereas we got the MFI T here in the USA) so I think this was a later evolution.
Now, you've got a 1967 casting date on the side. That's VERY helpful insofar as that can help figure out if it's the right one for your car. How many dots around the circle, I can't see from the photo?
Generally the successor model year began in September (the Factory shut down in late August) so if it dates from 9-10-11-12 of 1967 then it's definitely a 1968. The casting numbers and date codes GENERALLY predate the production date of the car by about two months. The gauges in my April 1, 1966 production car are stamped 2-66 as are the VDO senders-- the wheels date from 3-66 and so on. So a casting date of anytime after about July, 1967 would probably be appropriate for a 1968 Model year car.
On the Studs, they are definitely DIN studs, appear to be the correct length for original manifolds. Lots of manifolds have longer, fully-threaded studs that are intended to be used with phenolic plastic manifold spacers, which can help with fuel boiling. Yours look ok.
How about a detail shot of the center runner? We should be able to see the spot where the factory machined the flanges flat after the manifolds were "chem film" coated.
See my other thread where I copper-plated my magnesium manifolds in preparation for cadmium plate. . . or I could just leave them copper, that would throw the judges for a loop!
Hope this information is helpful to you. Good luck.
1966 911 #304065 Irischgruen
John,
Thx for the information. My car was built in early fall 67. I've attached more pics as you suggested. I don't see any machining on the center runner so based on your comments this leads me to believe that the manifold was originally unpainted. Do you concur?
Thx,
Dan
John,
The longer studs are on the heads, not the manifold. Porsche started using the phenolic insulating spacer with the 1971 911T.
When installing insulating spacers on earlier heads, you need longer studs. I have two Factory phenolic spacers on many of my carbureted engines – including the tall 906 magnesium manifolds (just ported to match).
Are there aftermarket phenolic spacers for use between the carburetor base and the manifold?
Dan also has a thread on Pelican that I addressed.
http://forums.pelicanparts.com/porsc...ld-finish.html
Best,
Grady
The black finish is Teflon, meant to keep gas droplets moving. I wonder if it worked and if anyone has restored them with Teflon coating.
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