Risk of Pulling Stuts. History of engine 6272414. 911/85

[HKZ Bob]

Hello folks
is the team able to verify me case no. Are my assumtions OK
6=76
27=2.7
2414 serial no. Is this correct. Where these engines equipped with hydraulic chain tensioners.
Engine no.
6272414. There is another number close to that on that is 911/85

How can I check if if have defect aged studs. Should I execute a pull test with a cylinder attached and 25% moge torque as required. Thank you 911 team.

[304065]

http://members.rennlist.com/tweedt/Stoddard3.jpg

6= six cylinder 911
2= 911S type (for that year, anyway)
7 = 1977
2414= sequential number

engine ID

[HKZ Bob]

John thank you that was fast. What about my other questinons?

[Eagledriver]

Your case should have dilivar bottom headstuds if the case has not been rebuilt. There are many threads on here about rebuilding 2.7 engines. If the case hasn't been timecerted/casesavered then it must be done. All the lower studs should be replaced and I would use new Dilivar studs. Others will recommend steel or other aftermarket studs. The test you describe will not tell you anything. The load on the studs when the engine gets hot is much greater than the test you describe.

-Andy

[Dan in Pasadena]

I guess you learn something new every day but I have never heard of stock 2.7's with Dilavar studs. I thought Dilavar only came on SC's/3.0's. I have also always heard to use steel studs and case savers on the 2.7.

Is that not the consensus recommendation?

[HKZ Bob]

Thanks Dan & Eagle. What means timecerted/casesavered . How does it looks like & which are the lower studs. Do you mean the side where the oil pump is bolted on.

[Dan in Pasadena]

Timecerts and Case Savers are two different types of threaded inserts installed in the case which then accept the studs which hold the cylinders and heads in place. They do not pull out as the studs directly in the Magnesium can. I am by no means an expert but I have always been told with the Magnesium cased 2.7's you want the more aggressive threads that Case Savers give you over the ones on Time Certs.

Sounds like you need to buy Wayne's 911 Rebuild book. There are discussions in it of the use of these; and of which studs to use. Again, I have always heard to revert to plain steel studs although I have also heard there are those that advocate the fully threaded 993 type studs.

The "lower" studs are literally the ones near the bottom of the engine; those closer to the ground! They (of course) are closer to the exhaust as the exhaust exits the engine from below. If I remember correctly Dilavar was Porsche's attempt to use a material that would have the strength of steel but would also mimic the expansion properties of the aluminum cased 3.0 engines. The knock on them is that if nicked or damaged on the surface the nick can be a starting point for corrosion that ultimatley can lead to breakage. Again, no expert but I THINK that is how it happens. Someone more knowledgeable than I will chime in here and provide clarifications or greater detail.

[HKZ Bob]

Which studs are affectec by getting pulled out.


Eagle you said lower studs. Here a picture point then out for me.
Thank you.

[dion914-6]

Flip the case over and take another picture. The studs everyone is talking about are the longest studs that surround each barrel (3 big holes in the side), and the are the ones furthest from the bottom of the last picture.

I also thought dilivar lower studs weren't introduced until the 3 liters. All of the studs I removed on my 75 2.7 were steel.

Dion

[Dan in Pasadena]

HKZ Bob,
Looks like you are already deeply into this engine. And also looks like you're doing it yourself on the home work bench? If you read Wayne's book (as well as extensive discussions here in the past) you DO know you should send the cases out to have the Case Savers precision installed, right? So they are perpendicular to the spigots? Otherwise if you do them at home you could end up with the studs sticking out all out of whack like a porcupine. That's an exageration of course, but precision installation (so they're all where they should be) is critical. Best of luck. Post your progress pix.

[HKZ Bob]

Hello thank you for your help.

I have two issues. My case is from Florida. It was full of oxide. White powder inside. It was degrease very good and than stored. so I oiled it again to stop further oxidization
See at picture, the white sections. Do you think the long storage
aging could weaken the durability of the case.


Attached two fixing methods I found in my garage.
Are these repair fixes similar then the above mentioned.

I have a helicoil and some other product which works like a thread drill.

You are machining a hole in 10.2 and inserting the thread fix. It automatically cuts in. Are these similar as in Wayens book.

Greetings

[HKZ Bob]

Dan thank you for the help. Yes precision is requested, but why replacing all the threads if I can make a pull test to figure out the bad ones from the good ones and have only the defect ones replaced.

I assume the bolts thread are a M10
the thread slope is 1.5
the quality s a 12.9 steel
then the torque is 90 Nm.
This is out of a bolt table.

So if I torque the with max force, before the elongation starts and it survive this test than it should be good for a reuse.

Who agrees on this test and who don't.
You are not replacing you Porsche if have not tested the performance before you evaluate to buy a new one. I am the guy who like to figure out and avoid additional work if not necessary.

Greetings Bob

[dion914-6]

My opinion....

My 2.7 case is at the same state as yours (but no oxidation), but I have removed the old head studs already. They were all in there extremely tight and didn't appear to have any issues. however, I removed them because it's easier to do the work now then find out the hard way once the engine is back in the car. You would be sick if you only replaced a handful of studs and promptly broke one or pulled one after getting the engine back together. It happened to a friend of mine with his turbo, and that's an aluminum case.

An ounce of prevention is worth what to you?

Dion

[Dan in Pasadena]

Originally posted by dion914-6
.....it's easier to do the work now than find out the hard way once the engine is back in the car. You would be sick if you only replaced a handful of studs and promptly broke one or pulled one after getting the engine back together. .........An ounce of prevention is worth what to you?

We all do what we're comfortable with. In my case I agree with Dion completely. How manytimes do you intend to pull your engine to rebuild it or to address broken/pulled studs? My answer? Once, preferably.

I've got 127,000 miles on an unrebuilt 2.7 with no external oil cooler. My studs have not pulled. Compression is good; car runs great. The thermal reactors and 5 blade fan were swapped out very early in its life. But even though that is it's condition why would I REMOTELY consider testing my luck by following anything other than the prudent "address-the-issue-once" approach.

Bob, If the prospect of having to re-pull the engine and tear it down for a later broken or stripped stud represents nothing to you but another chance to work on your engine (i.e. "fun") then follow your approach. If I were like that then I might consider it. But I am not a true gearhead. I wrench because my finances require it and I (once) was fairly good at it. Now I'd really rather do it in minimal doses. YMMV. Best, Dan

[HKZ Bob]

Will I be fine if I replace all my studs with divilar studs, due to the fact
they have a better expansion ration compliant with the cylinders? .

A definition questions.
"Case saver:" They are repairing a worn thread and thats why they are called case savers.

If if loose all the cylinderbolts and the case threads are OK. No damage at the extract operation, do I still need to install a case saver?

[Eagledriver]

Bob,

It would definitly be prudent to put Casesavers in the headstud holes. Dilivar studs started in 1977 on the bottom row of studs but I'd put new ones in anyway since they have a habit of breaking at this age. I know you want to do the minimum to save money and I do the same when I build an engine but these 2 things are money well spent. There are also a couple of other studs that should be timecerted when the engine is apart as a matter of course. A good engine shop with experience can make sure you get the studs you need timecerted. One in particular is the stud next to the intermediate shaft bearing. Be very careful to not overtorque any of the studs on the case especially the long ones at the rear around the number 1 main bearing.

-Andy

[HKZ Bob]

$Thanks All for the help

Need some more help

I have a second engine case no of an 911 2.7

Engine no.
62301113
911/52
0170

901.101.102.4R
901.101.101.5R

My spigots are 96.6 mm with 90mm cylinders.
These DATA do not match with all the charts.

[HKZ Bob]

How does my case no fits to the serial no.

[HKZ Bob]

[HKZ Bob]