1977 911s

I've heard that the head studs were partially changed during the 1977 production year. Does anyone know what engine number the change was started?

Good question I would like to know that also. I have my engine out of the car right now and have checked my studs, all are tight but I still want to change them next year.
Shawn

Count me in also! I have been looking through Bruce Anderson's book, and he seems to have conflicting info. In some places he says that the dilivar studs were used for all of 77, other places he says that were changed part way through the year. The same for the valve guides, does any body know when they switched to more durable guides? I would post page numbers from the book, but am at work right now.
Thanks, Craig

Dido here.

Matt
77 911S

I thought Bruce said that the valve guides were all upgraded for 1977, but I'm at work also and can't check the book. I know there is another site where Bruce would personally respond to these type issues, but I lost the address when I updated my PC. If anyone knows that site please let us know.

Like I said earlier my engine is out of my car, I checked the studs 3 months ago and didn't see any difference in the top to bottom, The valve covers are now back on and unless needed I don't want to take them off until next winter when I do the stud and of course the valve clearances. I assume someone here knows by the serial #??????

Bruce Andersons book states "...and some of the late-1977 2.7 911 engines use Divilar head studs. The 911 turbo engines use all 24 Divilar head studs, while the normally aspirated 911 engines use 12 Divilar studs just for the bottom row.."

It doesn't say when the change was made in regard to serial #s.

Shawn

Found the page in Bruce's book that confuses me about the Dilavar studs(I knew dilivar didn't look right ). On page 114 it states that: "Unfortunately, Porsche's change to Dilavar head studs did not start until 1977, when Porsche changed the lower row of head studs to studs made of Dilavar material".
Dsentel, you are right about the valve guides. He says they were changed in 77 to the silicon bronze alloy. (same page as a matter of fact: 114)
My car runs like a top, passes emissions beautifully, and is a kick to drive, so I am just hoping for good news here.
Craig

After reading this thread, along with my own comments, I found Bruce Andersons's web site and posed the question to him about when the studs were changed to Dilavar, did he know the engine serial numbers when this change took place, etc. The following is his reply to me, in full:

"Sorry, no I don’t know when. I have never seen specific information on the
change. Remember tech bulletins were a secrete back then, they didn’t want us
to know that kind of stuff.

I was working on the cars on a regular basis back then and some of the 1977s
had the good valve guides and some didn’t. Also some cars had the Dilavar
head studs and some didn’t.

Bruce Anderson www.911handbook.com "

So I guess some of us with 77's may be lucky, and some may not. My car was built in April of 77, so it was built some where in the middle of production. I heard that German model years go from August to August, so maybe mine is late enough for all the changes.

i have never seen dilivar studs on a 77 alloy case. the 930s had all 24 with the aluminum case. then SCs had the lowers only. so maybe the late 77s were actually SCs made in 77 as a 78 model!?

i have never seen dilivar studs on a 77 alloy case. the 930s had all 24 with the aluminum case. then SCs had the lowers only. so maybe the late 77s were actually SCs made in 77 as a 78 model!?

Regarding the Dilivar studs and whether or not an engine has them, it isn't just a matter of production line changes. Throughout the Southern USA, by early-to-mid '76, dealerships and Porsche-Audi knew there were severe problems with the smogged 2.7 engines, and the factory knew as well! At some point there was a very quiet 'program' to rectify engine problems that resulted in the dreaded 'head-slap' noises that were coming into dealerships. In many cases, reconditioned engines were being installed into cars, some repeatedly, and customers were not being informed what the 'fixes' were being done under the warranty work, just that it was a 'known problem' and the fix was a replacement engine for the forseeable future, under warranty. At some point around summer '76, the 'magic bullet' officially, but secretly, became the Dilivar stud retrofit in any 2.7 with headslap due to pulled studs. So, many '75 and '76 model cars still under warranty were retrofited with Dilivar studs, and some beyond official warranty limits when documented history of continuing problems existed.

I suspect, but can't prove, that a shortage of Dilivar studs meant that the first large quantities were sent to the USA to retrofit those cars out there with the 'known problem' ... and that production '77 engines didn't all get them until enough to satisfy US dealer requirements had been fulfilled. Then, as quantities of Dilivar studs became sufficient, production engines got them, and more 'spares' were sent over to the USA for the secret program to retrofit all '77 engines, as they came in for regular service, whether problems had shown up or not!

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Warren Hall
1973 911S Targa

How does a poor slob like me know it it was done to a car or not? Do you have to put a wrench to it, or are there tale-tell indicators?

Anyone ever watch Magnum PI? Remember that Magnum always thought Higgens was really Robin Masters?

I think Warren is really Bruce Anderson. Or at least maybe he taught Bruce...