Between good tool recommendations like this and Amazon one click/one day shopping/shipping, I'm going to go broke...

 

Second the recommendation for the transfer punch if there's at least one full unoccupied thread to center the transfer punch. From your picture it doesn't look like that's the case.

For those playing along at home, a transfer punch has a cone end centered on the end of a pin punch. They come in sets with lots of sizes of the "pin", so you'd typically select the one that just barely fits in the minor diameter of the threads in the aluminum. Advantage of a transfer punch is that it will put a ding in the bolt based on the center of the hole or threads guiding the punch. But they only work if you have enough material to actually center the pin, and that's where I was not seeing enough to make a transfer punch a practical option.

The cam cover bolts are 6mm threads, so using the 6-7 lbs/ft tightening limit is reasonable. Go lower if possible, since you really don't want to stretch the bolt at all if possible. You'll be using your 1/4"-drive torque wrench or a torque-limiting screwdriver rather than a larger (3/8'- or 1/2"-drive) torque wrench, as those larger ones just aren't close to their design ranges at the desired torque. 12 lbs/inch is the same as 1 lb/ft, so your target tightening will be in the 60-70 lbs/inch range that your smaller wrench uses. You'll be shocked at how small that tightening torque actually is. Above all, resist the urge to "just snug it a little more" because you feel it needs it, or because there's some seepage at a gasket that you feel a little more pressure might solve. It won't solve the seepage but it will stretch the bolt. To get a little more pressure you'll want to install new bolt seals and add the thin washers to all the cover bolts per Porsche's later recommendation.

 

If the bolt broke from fatigue or from a flaw, it should "jump" out of that hole. A "reverse" drill bit will take it out, in seconds.

If the bolt broke from "threading issues" (bad threads on either the bolt or in the head) or it was "cross threaded", you will know instantly.....it won't "jump" out and you could be in for an adventure.

If you have to drill it and use any kind of a removal tool....do not, under any circumstances, break off the drill or the removal tool in the head. Drill it perfectly "dead center"!

If this job really turns to **** (like the above), there are some super specific tools and steps to "recover" from here.

I've removed, machined out, welded, and re-machined more things that I can count, in my career. People "run out of talent" very quickly, when the simple stuff gets more complex.

gb

 

The transfer punch I recommended first was because Greg Brown provides them in one of the kits he sells. Without that I would not have known about them. Thanks Greg. I have gone on to use them to transfer holes from the early oil pans that hold the screen and cloverleaf to the oil pan I am using for the stroker and GTS oil pan baffles. Their holes act as templates. Pretty cool stuff. One of the things I love about this forum are the tool recommendations. The latest is the long handle 19mm offset box wrench I use to remove the bellhousing bolts. That was worth the cost of membership right there.

 

The bolt screws in and out of the hole easily ie. there is no corrosion or resistance. IF I can get a center hole started I think it will come out pretty easily. I ordered those reverse drill bits and a few other hole centering tools today. Say a prayer for me, I'm starting to think this car is cursed.

 

..

 

This car will not defeat me!!!

 

Truthfully, this is the "every single day" (sometimes more than once a day) stuff that we deal with, while working on old cars.
If this is what defeats you, you've picked the wrong hobby.

Wait until you try to set the cam timing on your 968.....that's what is tough.
The factory instructions are absurd, unless you are building an engine out of all brand new pieces, on the factory floor. 95% of those cars that I've seen over the years (we don't work on them, anymore, thankfully) had the cam timing completely incorrect and ran poorly.

 

Oh............well I guess I'm a little out of my league here.



That's what I finished doing before I broke the bolt.