964 valve covers on 2.8 twin-plug??

[Steve in SLO]

I am building a twin-plugged 2.8L engine, and thought that instead of putting holes into my lower valve covers, I would use 964/993 covers. The bolt pattern lines up, so I am told. Does anyone know why this should not work? If not, does anyone have a good used set to sell?
TIA,
Steve

[Tyson Schmidt]

I've heard it works fine. One cavaet. You need the special studs with the built-in shoulder that limits the amount you compress the rubber gasket.

[ChrisBennet]

Steve,
When I built my twin plug motor I had this very same thought. I've seen late 3.2L cam towers with 964 part numbers so I thought "Hey I'll get some 964 covers and plug wires and I'll be all set". I tried to find some 964 valve covers used but I couldn't so I tried 993 ones instead. I also used 993 lower plug wires. Here's what I learned:
- 993 lower valve covers have aluminum inserts with holes for 6mm studs - not the 8mm ones of older engines.
- If you drill out the holes to fit 8mm studs the valve covers seem to fit OK but the covers leaked (but not from the stud holes).
- 993 upper valve covers do not fit period.
- The 993 lower plug wires have nice thick protective sleeves over the wires. I suppose this was done to cope with the high heat in this area.

I had to get the car together for a track event so I used some aluminum ones but I'm going to try 964 valve covers again. Let me know if you learn anymore on this.
-Chris