chris928

Are the valve covers Aluminum or Mag? I hear mag doesn't polish well, is that true.

I'm suprised that one of the big 3 don't provide these on an exchange basis. I had a 240Z and could trade my valve cover for a very nicely polished one for about $100. Found this out after spending about 10 hours polishing my own... Don't want a repeat on the 928.

Dave H.

i've never heard of anyone polishing mag, it's always coated or painted as far as i know. even if you could get a polish on it, you'd have to clear coat it as you can't leave it bare. bare mag will corrode just looking at it. working on aircraft, if you scratch or chip the paint on a mag part, it needs to be fixed right away. and painting mag can be a royal PITA.

while i'd love my intake and valve covers pilished, it ain't gonna happen.

there's a process called "tagnite" that looks like it would be a good base for painting...

the cool trick would be to have someone CNC some aluminum copies.

and while we're at it, put the oil cap on one of the covers and install a block-off plate where that silly leaking filler neck gasket goes... <img src="graemlins/cussing.gif" border="0" alt="[grrrrrrr]" />

chris928

what do they do on mag wheels?

chris928

BTW what about these? they look polished

<a href="http://www.928gt.com/images/Nology/89S4-Nology.jpg" target="_blank">http://www.928gt.com/images/Nology/89S4-Nology.jpg</a>

Mike Schmidt

I'm not sure about the earlier cars, but on the S4 and later the valve covers are magnesium. The intake manifold is magnesium too, and a local S4 owner has the side plates of his polished. Dave Shaeffer did the painting and polishing on that. There are some pictures of it at <a href="http://www.smidgie.com/928/intakes/" target="_blank">http://www.smidgie.com/928/intakes/</a>
The problem with the valve covers is that they usually aren't very good castings. It's common for them to have pits and various other appearance problems once the paint is removed. You might want to contact Dave and see what he has to say about polishing them. His web site is at <a href="http://members.rennlist.com/mechanic/" target="_blank">http://members.rennlist.com/mechanic/</a>

Dave H.

don't know the process for mag wheels, but it's prob'ly chem treated.

on bare aluminum, you use a chemical called Alodine, which actually creates a very thin inert corrosion layer, which acts as a block to further corrosion. after you alodine aluminum (you wash it off with water) you them prime and paint.

mag uses a similar process...

Dave H.

those covers look painted to me...

DR

Hi Chris,

[quote]Are the valve covers Aluminum or Mag? I hear mag doesn't polish well, is that true.<hr></blockquote>

The Valve Covers are aluminum with mag content. No sure what the ratio is but there is enough mag to cause problems with Jet Hot type coating (the extreme heat of the process causes the mag to bubble the coating).

[quote] I'm suprised that one of the big 3 don't provide these on an exchange basis. <hr></blockquote>

We are gathering up supplies to offer an exchange program ( have a GT set available now), but it will be powder coated, not polished (see below for why).

[quote] BTW what about these? they look polished
<a href="http://www.928gt.com/images/Nology/89S4-Nology.jpg" target="_blank">http://www.928gt.com/images/Nology/89S4-Nology.jpg</a> <hr></blockquote>

That is the engine of my (ex) 89S4 that I polished and coated many years ago. The side covers of the S4 intake are pretty much pure aluminum and very easy to polish to a mirror finish, The Main intake section is mostly mag and can be polished but will oxidize almost immediately (this one was painted with Stainless steel header coating using a sponge for a cast look). The Valve covers were indeed polished, but close up it did not look very good due to the "pockets" of mag and the porus nature of the casting (due I think to the mixture of mag with the aluminum) . It is for this reason that coating or painting the valve covers will give you the best long term results.