What are the different valve covers?

wayner · 10-07-2011, 08:07 AM

My 3.0 has turbo lower valve covers but I was told that the uppers are not turbo.

Since the 3.0 has a 930 case, I assumed that meant everything including the valve covers were 930.

I have also noticed that some uppers advertised as 930 have the porsche script and others do not.

Can anyone shed some light on which ones I should have ideally for an oil tight low maintenance engine?

Thanks

P.S.
Yes, I have done a search

wildcat077 · wildcat077's Garage

On my 89 3.2 it seems the lower are the turbo "ribbed" covers and the top ones are regular 911 non ribbed ones.
Not sure if the car came like that or the PO changed the lower covers ...

Cheers !
Phil

wayner · 10-07-2011, 09:10 AM

Thanks Phil

My lowers are turbo ribbed as well, and was told by the prev owner that those were upgraded turbo.

Since the 3.0 is a 930 case, I am confused as to what consitutes a "turbo" valve cover. Did they only come on turbos, or any car with a 930 case?

As for the uppers, I've seen uppers that are smooth, advertised as 930, but some 930 with a script and some advertised as 930 without.

Is a turbo simply one with a 930 part number?
How can the differences in the uppers be spotted?
Do turbo uppers come with and without Porsche script depending on year?

wayner · 10-11-2011, 09:01 AM

Bump

Does anyone know?

Targalid · 10-11-2011, 12:20 PM

My understanding is that the lower covers are the ones that cause problems because they are on the hot exhaust side of the engine. They have more warping as a result plus oil tends to pool there so more tendency to leak. It is not necessary to have ribbed intake valve covers. The lower covers were ribbed to give more thermal stability. The upper covers almost never leak and seldom need replacement.

KNS · 10-11-2011, 12:25 PM

Starting in 1980 all 911s got Turbo lower valve covers. The uppers I don't think ever changed and had 901 part numbers all the way through 1989.

dtw · 10-12-2011, 04:41 AM

Quote:

Originally Posted by KNS

Starting in 1980 all 911s got Turbo lower valve covers. The uppers I don't think ever changed and had 901 part numbers all the way through 1989.

Yep. They switched from Mg to Al at some point, but the casting was the same. There's no such thing as 930 uppers, just lowers.

wayner · 10-26-2011, 11:31 AM

Perfect

Thanks!

wayner · 11-03-2011, 04:45 PM

Ok, just pulled the upper covers and here is what I have:

901.105.115.0R (light weight - magnesium??)

901.105.115.02 (much heavier maybe 3x or more - everything is thicker, including inner webs)

QUESTION: should I just leave them, or switch the magnesium one out for a later one?

Walt Fricke · 11-03-2011, 08:52 PM

Wayner - I can tell you aren't a racer, because if you were you would not ask this question, as you would be looking for another mag cover.

If you aren't having leaking issues, I'd just leave what you have.

If you are having intake valve cover leaks, consider which cover is doing the leaking. Then carefully check that cover. The covers can get warped some from overtightening (which we all do in our attempts to stop leaks).

They can be trued up. A near industrial width belt sander will do this. If you have a mill you could use it. And I suspect that a large sheet of wet/dry sandpaper on a large sheet of plate glass might allow you to true the surfaces by hand - running the cover back and forth over the wet sand paper, with the glass serving as a true flat surface.

wayner · 11-04-2011, 04:55 AM

Thanks Walt.

I really like the mag cover, but it is the one that is weeping.

Thanks for your advice on fixing that.

Targalid · 11-04-2011, 08:52 AM

I use the Pelican silicone valve cover gaskets. All valve cover leaking stopped.

RoninLB · 11-04-2011, 10:32 AM

I bought redesigned gasket lower covers from Imagine Auto Inc in Kansas

in 2007 the cost $295 + $15 shipping

it's a class act

DG624 · 11-16-2011, 04:04 PM

I just had my valve covers ceramic coated to reduce heat but I didn't check to see if the mating surface was perfectly flat. I assumed that the valve gasket would compensate for any irregularities. I also had the CAT ceramic coated to reduce heat at the valve cover.

Walt Fricke · 11-16-2011, 08:19 PM

I would have thought it a good thing for some of the heat generated within the cam towers and whatnot to escape via the valve covers. Just that much less work for the oil coolers to do.

If a guy thought that this coating would reduce the inlet temperature for the induction or cooling air, he might get a better result with direct ducting to outside air. A respected engine builder once told me he built an elaborate air box for carburetors, so all the air came from above. Dyno showed zero improvement.

DG624 · 11-23-2011, 10:41 AM

I used the Techline coating to reduce heat from the valve covers and shed oil internally. This coating helps to reduce the engine heat on the lower and upper valves and eliminates oxidation.

Welcome to Tech Line Coatings, Inc.

Flat Six · Flat Six's Garage

Quote:

Originally Posted by DG624

I used the Techline coating to reduce heat from the valve covers and shed oil internally. This coating helps to reduce the engine heat on the lower and upper valves and eliminates oxidation.

Welcome to Tech Line Coatings, Inc.

Plus they look great. Any more pics? Perhaps of the cat too?

KTL · 11-23-2011, 11:10 AM

The Techline ceramic coating looks excellent. But you do bring up a good point about the gasketing surface remaining true. I've had some ceramic coated exhaust pieces come back from Jet-Hot with really poor gasket surfaces. To add insult to injury, the ceramic coating is very hard and therefore makes it hard for us to clean up any imperfections. I hated to do it, but had to take a bastard file to my exhaust flanges to flatten out some of the imperfections.

Walt Fricke · 11-23-2011, 08:45 PM

Now you have me really confused. You used a ceramic coating on the valve covers to reduce engine heat on the lower and upper valves?

Are you saying that heat from outside the motor gets in to the valve spring/rocker arm area? Giant, glowing red turbos on each side right next to the valve covers?

Ceramic coatings certainly will reduce heat flow, keeping the hot side hotter, and the cold side colder. I am not seeing how this will help in this location, though. The oil starts out relatively cool, and after valve stems and springs and cam friction and whatnot heats it up, carries away some of that heat as it moves to the pump.

Flieger · Flieger's Garage

I am sure with turbos there it would be good to have a ceramic barrier. With normal headers maybe a wash. What I would do is coat the exhaust inside, then leave the valve covers without a thermal barrier.