Adapting 964 Valve Covers on 911/930 Engines

[garrickl]

I recently twin plugged my 930 motor keeping the factory 3.3 heads. I picked up a pair of 964 upper and lower valve covers thinking that they could be adapted to work with my new twin plug heads. The upper valve covers are fine ... however, the lower exhaust ones [ # 3 & #4 spark plug ones ] run into the chain housing. I could simply cut off a portion of each side so that these would fit but wanted to know if anyone has a better idea or if this could possibly cause other problems. Also ... if anyone is using this setup .... what type of valve cover gaskets are you using? My other option is simply to drill out the 3.3 lower valve covers and use them. Your comments and experience will be appreciated.

[emcon5]

Hi Garrick,

Ted at German Precision drilled lower plug holes in my lower VC's. Probably wouldn't be very expensive.

Tom

[ChrisBennet]

Garrick,
I tried this with lower 993 covers. I drilled out the aluminum inserts so they would fit over 8mm studs. They leaked. I'm going to try it again this winter with some 964 covers. This time I think I'll use 6mm studs. Maybe I can get some funny 8mm/6mm studs to make the conversion easier.

As I see it, the 964 lower covers have a couple of advantages if you can get them to work:
- The 964 covers do a pretty good job of holding the 964 wires and the wire ends make a nice water tight seal in the cover
- The 964 (lower) wires have an extra protective sheath over them to protect them from the hot exhaust.

Let me know how you make out Garrick.
-Chris

[garrickl]

Ted at German Prescision drilled out my 964 covers to work with 8mm studs. The problem I have is that the casting around the #3 & #4 spark plug holes hit the cam towers ....... and, if I want to use them I need to grind them down or off. Also wanted to know what kind of lower valve cover gaskets people have tried and used and which are best in preventing leakage. I will let you know what we decide .... but was hoping for someone who has done this to let us know their success or failure story.

[garrickl]

Well this weekend I answered my own question and the answer is yes and no. You can get the 964 left side exhaust cover to fit by trimming back the casting ring for the #3 sparkplug but the turbo oil pump location makes the hole\space so small that you will need to put the plug connector in before tightening down the valve cover ... and Magnacor KV85 wires will not work ... the spark plug connectors are too short so you will need to use 964 wires ..... I did not want to waste a brand new set of Magnacor twin plug wires so .... I decided to have my 930 exhaust covers drilled out to use. Anyone want to make me an offer on my modified 964 valve covers .... complete set, top and bottom with fresh silver powder coating. My lost your gain.

[Wayne 962]

I have never seen this work well on a non-3.6 engine. Drilling the Turbo valve covers is pretty cheap, and very easy...

-Wayne

[911pcars]

From the responses on this thread, can I assume the early valve cover gaskets work with 964 and/or 993 valve covers?

Sherwood Lee
http://members.rennlist.org/911cars

[garrickl]

You are partially right on this Wayne. I should have checked this out further before diving into this. What I have learned is that the Magnacor twin plug wire set spark plug connectors are too short to work with 964 covers. So what I did was simply drill out the factory Turbo exhaust valve covers and now everything is fine. These 964 covers will work I believe only if you are using the factory 964 wire set. So if anyone on the board is building a twin plug setup on their 911 or 930 motors and plan to use the 964 or 993 twin cap distributor and factory wire set ... these covers are available. I have the full set of intake and exhaust. $100 or BO.

[ChrisBennet]

Originally posted by 911pcars
From the responses on this thread, can I assume the early valve cover gaskets work with 964 and/or 993 valve covers?

Sherwood Lee
http://members.rennlist.org/911cars

Lee,
I don't think so but maybe. The later valve covers have grooves for rubber gaskets.
-Chris