[sc_rufctr]

I love mine because it's a lot of fun to drive and it's simple and therefore nothing much goes wrong with it.

Originally Posted by peteremsley

Don't have mine any more, but it was the smell of burning oil coming in through the vents as it drips from the un-sealable lower valve covers onto the heat exchangers.

From Peter Z on this board.
I've never had a leak, not one drop since reading an implementing this more than 10 years ago.

Something to consider. The following is an excerpt from a copyrighted work written by me on this very subject. Cheers!

A Logical Discussion:
Topic: Rocker/valve cover retaining nut torque for Porsche 911s built between 1965 and 1989.

Rocker covers evolved through four generations; (1) aluminium upper and lower (6-nut type) used from 1965-67, (2) magnesium upper and lower (11-nut type) used well into the ‘70s, (3) aluminium upper and lower (11-nut type) used on most ‘77s, early Turbo Carreras and early SCs, and (4) aluminium upper covers with heavily reinforced lower aluminium covers often called Turbo covers.

Gaskets also evolved; originally made of cork, then graphite composition, then a version with a silicon bead (lower) as well as ultra-thin, firm, self-sealing gaskets that ranged in colour from green to almost blue. Hardware, always 8mm, stayed the same with one exception – very early 2.0 911s were frequently seen with non-locking upper cover nuts used in combination with wavy-type lock washers.

That’s the history. It is fact that the early cork gaskets could squeeze out from between the early covers and cam housings, especially under a heavy hand tightening the nuts. As a side note, my shop used cork gaskets (lowers were available for both 6-nut and 11-nut covers) to help seal up leaks caused by warped magnesium covers. Those covers were never “torqued,” just tightened by feel and using the visible gasket edge as an aid.

Along came lean burn engines, thermal reactors and excessive heat, which, in a way, was responsible for the development of the superior gaskets that we have today.

All the while, a plate (used through about mid-’83) on the bottom of the engine, usually referred to as an oil screen cover or a sump plate, saw fewer gasket changes; from thin paper to graphite, then to an improved even thinner graphite. No change to the torque spec for its 6mm (quantity 8) nuts was made – that held at 10Nm (7 lb/ft). Think about that for a moment; tiny 6mm nuts, each used with a wavy lock washer, tightened to 7 lb/ft.

Back to a set of rocker covers, sealed with graphite upper and lower gaskets. Those gaskets were quite firm, and about 1/3 the thickness of cork versions, it made sense that more torque could be applied. Certainly the hardware was up to the task, after all, it was identical to the crankcase perimeter hardware and the chain case to crank case hardware – 8mm Nylok nuts and aluminum sealing washers. Specified torque for that hardware? 25Nm (18 lb/ft).

The period through which gasket technology changed was interesting for my shop. Many of my customers bought new cars, and some opted to have us perform the required 1,000 mile service, rather than have it done at the dealer by an unknown (yes, Porsche pre-approved this and all warranties remained intact). We noticed, while doing those jobs, how tight the factory-installed rocker cover nuts were, and realized it was due to the new gaskets, and eventually better lower covers. We re-checked the Spec books (by this time we were servicing SCs), and decided that the “All bolts (fasteners) on crankcase and camshaft housing, M8 = 25Nm” had to take precedence over the note about a “cover, M8 = 8Nm” which co-incidentally appeared in the torque spec list with the camshaft bolt/nut spec. So, we used 18 lb/ft on a large number of cars, new and old with the latest gaskets, discovered that dis-assembly at the next scheduled service was perfectly normal, and made that spec routine for all except the cars that used cork gaskets.

We have now reached the point where the latest version sump gasket became identical to the chain case, crank case gasket. To review, the torque for the 6mm sump plate nuts is 10Nm, the torque for the 8mm chain case nuts is 25 Nm. The rocker cover gaskets that have been available for many years are thin, firm, and self-sealing. Rocker cover hardware is 8mm. Why would one consider 6 lb/ft – ONE LESS than the considerably smaller 6mm sump plate nuts, reasonable and appropriate for that 8mm hardware?

One must conclude that the 6 lb/ft spec; (1) was a typo (M8 instead of M6) that turned into a monster, (2) was a correct spec, but for original rocker covers using cork gaskets, or (3) was that it referred to the [3] 6mm bolts that secured the “cover” at the end of the camshaft inside the chain case, and two mistakes were made – one a typo and one in translation.

My personal belief is that #3 above is correct because; (1) the reference to a “cover” with “M8” hardware appears with the torque spec for the bolt/nut on the camshaft, and (2) that “cover” is called a “chain case cover” in later Porsche repair manuals, is noted to have, and is secured with 6mm hardware, and recommended torque is 8-10Nm (6-7 lb/ft). FYI: Later factory technical spec lists do a far more thorough job elsewhere as well. Not only did they finally correctly define “cover,” they itemize the specs for M8 hardware on the crankcase, M8 hardware on the cam housings, M8 hardware on the chain case, and included a spec not seen before – “Valve cover to camshaft housing.”
Logic.

With regard to this thread, 30Nm (about 22 lb/ft) is a bit high, but the OP's instincts are correct. The primary problem with the higher torque is that a chance exists where the aluminium sealing washers will collapse into the stud threads, making cover removal at the next adjustment interval extremely difficult.
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Keep the Shiny Side UP!
Pete Z.

Regarding torque specs, I'll say this one more time, with a couple of qualifiers. For 911s built through the '89 3.2 litre Carerra, that use 11-hole, aluminium lower covers, and use-once super-thin greenish blue gaskets, or green gaskets with a silicone bead, the torque spec for the 8mm Nylok nuts, used with proper German aluminium sealing washers, is 18 lb/ft.

It has nothing to do with heat cycles, or anything else. My shop buttoned up thousands of 911s using 18 lb/ft, many we didn't see until the next 15K service was due (many of our customers would have the in-between service done at an oil change only facility, or they would do it themselves). NONE had to return for follow-up tightening, NONE leaked, NONE had stripped hardware, NONE had hard-to-remove covers/washers, ALL were assembled using new gaskets, new washers, and new Nylok nuts.