I must be the luckiest SOB on earth
 

Preface: I bought a 911 SC two and a half years ago, with a broken head stud on #5 cylinder (yes I knew about it but the price was right).
I figured i'd get to it eventually, I didn't for a long time.

It didn't make any noise to indicate a problem, so I decided to drive it until it became a problem.
I heard and read that my engine would destroy itself, but I kept driving it until it started making noise, it didn't. I drove it hard, autocrosses, DE's, etc.

I put a turbo on it and cranked the boost up, thinking that would push it over the edge. it didn't.

I finally got around to fixing the broken head stud, here's the pictures. no damage at all to the cylinder or head. i am one lucky SOB or someone is crying wolf. I think I'm just lucky.
Having #5 break (which is in the middle) prolly helped.
http://forums.pelicanparts.com/uploa...1094009801.jpg http://forums.pelicanparts.com/uploa...1094009886.jpg

Wait till you measure it.

OK I'll bite, measure what? Flatness?

Yes, but from what it looks like from a fair pic, you may not have done much damage. If you were running a boosted SC motor, with a broken stud, then the chances would have been high that you would have melted a path out the side of the head and cylinder, but you may very well have gotten lucky. Nonetheless, if you mesured the surface, you will find its probably warped and will need to be machined., same for the cylinder.

It's the chipmunk cheeks that make you lucky ;) :p

Yup, you're prolly right, but if there is warping it is very minor compared to what I'd been led to expect. After I get everything cleaned up I'll throw it on the granite table and do some inspecting. I run a full machine shop so if I have to skin cut it won't be a big deal.
I was almost convinced I was going to have to scrap a cylinder and a head.

Oh, and Andy, I got it ;)

A few things (and I didn't get the chipmunk thing). First of all, make sure that you machine all of the surfaces for all three cylinders and/or heads on the same side of the engine. They absolutely must be the same height.

Secondly, your head stud was in the middle cylinder, which means that there were two more heads, one on each side, holding the assembly together. The cam tower adds structural stiffness that reduces the destructive effects of a broken head stud in the center. If this was on the end, the cam tower / head assembly would be cantilevering quite a bit more, and thus would do more damage.

-Wayne

Thanks for the input Wayne, I knoew about maintaining the deck height and the support from the cam housing, I probably got that information from your book.

I'm hoping that I won't have to do any machining but if I do it won't be a problem.
What surprised me was the fact that after over two years of driving thins thing there is no evidence of a broken head stud at all other than the carbon staining around it.
If I cleaned off all that staining it would be impossible to visually determine which cylinder had the broken stud.
Even a sucker gets a break sometimes.
BTW the chipmunk cheeks thing is prolly related to a picture on my website where it looks like my helmet is a little tight, http://forums.pelicanparts.com/uploa...1094137700.jpg

Indeed, that is where the chimpunk thing came from :D