I'm pretty sure the Dilavar studs started with the Nikasil cylinders on 2.7s To compensate for different shrinkage and expansion rates on these cylinders.

Thanks Luke, this is what I was thinking in terms of scope. Engine and tranny are out of the car already. Visually, except for the missing fan pulley and belt it looks ok. Some oil seepage, but not a ton of blowby. Just want to make sure I can pull it in and out of the garage if I have to ( I have a steepish driveway, it's a ***** to push cars up it by myself and the dog refuses to help ) .
It will also buy me a bit of time to decide on committing to a 2.7 rebuild or buying a bigger motor. I keep waffling on that. I'll figure it out.

Valve adjustment (back-side method- see Pelican Parts "Tech Article"), plus re-torque the head studs and replace the cover gaskets, it really tightens up the engine.

More power, less leaks.

My first experience doing this (2007), lots of people helped me through it.

http://forums.pelicanparts.com/porsche-911-technical-forum/357302-2-7-l-torque-headstuds-8-mm-allen.html

The second time I adjusted the valves only a few head stud needed any tightening. No movement at all in the following adjustments years later, it's staying tight.

PS: just my opinion, stick with non-synthetic oil, I really like Kendall GT-1.

http://forums.pelicanparts.com/porsche-911-technical-forum/662927-switch-kendall-oil-appears-have-solved-my-long-term-chain-rattle-issue-2.html#post8037258

Kendall gear oil is pretty good too, two types get the right kind - research.

PS-2: Seafoam cleaning - white billowing clouds of smoke - search it out.

Thanks K22. This summer/autumn is going to be a lot of ... something;)
I've done the seafoam thing on a Hemi . Not sure I can justify putting THAT much smoke and steam into the neighborhood air again ;)

I do seafoam treatments at night so neighbors dont see it. While the engine is out check the vacuum lines and replace thermostat and oil cooler seals. You can check for vacuum leaks by using a shop vac to pressurize the intake manifold and use soap solution to see if any bubbles appear.

Never retorque the head studs.

It would help if some explanation accompanied your statement.

Sherwood

Something occurs to me: A compression test on a cold motor isn't going to give anyone any good data, is it? I can't start the motor and let it warm up to do the compression test correctly, so it's sort of not worth doing until the motor runs again, right?

If the motor is good, even cold you should get good results, your looking for consistency from all six cylinders!:)

If the motor hasn't been run for a while, I'm not sure how valid a compression test would be. Stuck rings could loosen up after a couple of heat cycles, carbon could burn out etc.

I would, however, check for loose or broken head studs. DON"T try to torque them. Just put an allen wrench on them. If some are loose, you have a problem. At that point you will have to decide on your next course of action. If it were me, I would try to tighten them. I have heard of the nuts coming loose, but the studs are OK. Worse case is it won't tighten, well it was pulled anyway.

A couple of days ago I had an exhaust noise, so I examined all of the studs. One exhaust was loose. It turned out to be the nut that had come loose, but the stud was tight. I torqued it down = exhaust noise gone. It does happen.

Not a lot to explain, just that head studs should never be retorqued. They are locktited at the block. You might want to check with very light pressure to make sure the nuts have not backed off, but never loosen to retorque. That is a really good way to break a stud, or pull them out of the block.

100% accurate.

Also completely true - the last thing one would want to do is actually re-torque head stud nuts in a mag cased engine with dilivar studs (any kind of studs, for that matter, if case-savers aren't installed); for the reasons you mention and also that the measured torque values would be deceptive since the nuts had not just been lubricated (not like THAT!).

Pull the fan shroud and check for little critter nest. I found a large nest over the oil cooler on a 2.7 backup that I thought was in a mouse free zone. I think they like that green shroud. Lol

If you go to the link I provided you may see that one of my nuts was actually off and laying inside of the cover!

Hence the reason for reattachment. Would you have left it off?

I suspect the shop which did my first valve adjustment screwed up, like they did several other things, but have no solid proof. It is certainly possible they were attempting to cause more damage and loosened some nuts on purpose, they are unethical and incompetent and still wrench on Porsches. PM me for full details.

I did my research, and decided to go slightly below the full spec number out of caution (see link). Close enough was good enough and no studs were broken - thankfully.

Lose head stud nuts cause a loss of power, at least that's what my butt dyno told me. Snugging things up may help mitigate a few oil leaks too.

Like I said, did this procedure twice, third time all was still snug, not even going to check things on next valve adjustment, no reason to.

If you are going to check for lose nuts, use a torque wrench, set it for far less than full spec to start with, after that it's like Russian roulette.

http://forums.pelicanparts.com/porsche-911-technical-forum/67135-how-do-you-check-headstuds-when-valve-covers-off.html

http://forums.pelicanparts.com/porsche-911-technical-forum/454159-2-7-head-studs-torqued-some-turned-bit-i-used-search-button.html
I know the names on the forum which I trust.

I'm going to chime back in on this, because I could have added additional detail to my post above, and because there have been some interesting subsequent posts.

Put simply, the studs must be installed sticking a specific length out of the crankcase. When the nuts are torqued, the end of the stud will reside at the top of the threads in the nut, which is to say that the 'socket' portion of the nut will be of equal depth in each nut.

In my situation, the nut was loose. Obviously I couldn't leave it like that, so I removed it to check things out. A small magnet inserted into the head stud's hole showed that the stud was steel, so it likely wasn't broken. Since there are case savers in my crankcase, the odds were that the stud was generally OK.

So, rather than removing and tearing the engine down, I decided to torque the nut. If this failed, then the engine would have to be removed and torn down. Duh. I gambled that the nut could simply be torqued and I'd be on my merry way.

My information said that the nut and washer should be coated with anti-seize compound, and then should be torqued to 23.5 foot pounds. I did this. After torquing, the stud protruded into the nut in exactly the same way that all of the other studs resided in their nuts. Conclusion = the stud had not perceptibly moved, so I might be home free.

I started the car and my exhaust noise had vanished. Then I drove the snot out of the car, and nothing seems to have changed.

If for some reason all of this is incorrect, then the engine will have to come apart. But, what would a rational alternative have been? To leave it alone, with the nut loose? I don't think so.

Considering all the serious softball-sized wasp nests I found in the bay and undercarriage on this car when I took the motor out, I think it's safe to just go ahead and assume there are a few condos built under the shroud;)

Right, looks like some confusion on the different terms that people are using . . . no one here suggested that an unscrewed nut should be left off or that nuts should be left loose/finger tight if found to be in that condition, but there is a huge difference to re-installing a nut, checking nuts for looseness, and "torquing them down" (which implies putting the original torque value to all the nuts by using a torque measuring wrench = not a smart move).

I've read Walker's posts for years, and am fairly certain that in his quotes in post #35, he was talking about lightly checking them for snugness by hand with a ratchet - not grabbing the torque wrench and twisting with wild abandon.

hhhhhmmmmm

Ha ha - sweet! :D