Head studs advice 3.2

[lindemans]

Dear Pelicans,

I am preparing for a rebuild of my 1989 3.2 after 150.000 mls.

Head studs are original (top row steel / bottom row dilavar), but I know at least the dilavars should go out.

What's the general opinion here for a normally driven stock engine:
- replace all studs by steel (top and bottom row), or
- replace all by 993 full threaded studs,
- other ?

I know about the ARP and raceware options, but wonder if that is really needed for a stock engine after all.

Interested to hear what other Pelicans do in a rebuild...

[Eagledriver]

There is plenty of information on here about the options. My opinion is to just replace the lower studs with stock steel studs. That's what I have on my race car and they are working fine. Other options are no doubt better but I don't think they are worth the cost.

-Andy

[Flat6pac]

On my builds, for several years now the bottom gets replaced with vintage steel and it works just fine.
Bruce

[88-diamondblue]

+1 on using steel on the bottom. 3 years and doing just fine with the steel studs on my rebuild. A plus is that they are $10-12 each. The rebuild is a great project, just take as many pictures of dis-assembly as you can as well as when it's going back together.

[kenikh]

WAY too much info on Search...

[Geronimo '74]

For a stock engine you could probably do with just replacing the Dilavar ones with steel.
993 full threads is the next option, but more expensive.
Supertec, Raceware and ARP for anything that is not stock, or track oriented.

My rebuild will be street/sport, I went with Supertec. (Henry Schmidt on this board)
Great looking product, light, lifetime warrantee. Henry stands 100% behind his product + it is race proven.






Kenik was right too, lots of info underneath the search button

[lindemans]

Thanks for the quick replies and suggestions guys.
For some reason I cannot get the search option running properly; it keeps falling back to the standard list of postings.

I don't know why but a lot of Porsche parts have increased in price enormously; at least here in Europe. A set of Henry's steel is even cheaper nowadays than an original 993 set.

However I get more and more convinced about putting in standard steel for all 24 for my purpose. I don't race of track the car, although an occasional ski trip to the Alps in Austria does take me through Germany and speed-limit-less Autobahn ... so it does get kicked in the butt once in a while.
A couple a weeks ago, the 360 miles from Berlin to the Dutch border took me 3 hours, including a pit stop for gas.

[lindy 911]

I like the idea of having all the studs fresh and alike. For this reason alone I would recommend using all new studs of your choice and not have to worry whether the new studs were the same as the studs you're going to save. I think Supertec has the best stud because of the fine thread nut and the fact that the stud does not have to be perfectly setup in the case. They are nice pieces. I used them in my 10.5:1 3.0 SC

Lindy

[kenikh]

OK, sorry for the snide comment above. If Search doesn't work, I'll summarize:

Do not use old style Dilavar studs
993 fully threaded studs work very well, but as you mentioned, are overpriced
Stock steel are OK for small displacement and mild engine builds, but on a 3.2 you are asking for oil leaks. If go this route, retorque the heads with the first few oil changes.
Raceware and ARP make aftermarket bolts, but can have their own issues.
Best bet: irrespective of the fact that they more are affordable compared to 993 studs, comparable in price to ARP and Raceware, Supertec studs are the best bolt, IMHO. They are better finished, better detailed and don't fail or lead to leaks.

If in your budget, the Supertec studs will not disappoint, which is a risk from all other options.

[Geronimo '74]

Originally Posted by lindemans

I don't know why but a lot of Porsche parts have increased in price enormously; at least here in Europe. A set of Henry's steel is even cheaper nowadays than an original 993 set.

That is exactely why I went the Supertec route!!
I'm in your part of the world but ordering was easy peasy;
Henry is not the most talkative guy when ordering but he posts regularly on this board so lots of info if you get the search button to work!
His product is top notch!

[AlfonsoR]

I went with 993 studs and 964 nuts, based on Steve Wieners recommendation.

I think thermal expansion is an important part in making the engine last longer. Steel studs and material with similar expansion rates to steel, I think, induce unwanted stresses into the cylinder walls due to the difference in expansion rates of the steel stud versus the aluminum heads and cylinders.

Some people don't think thermal expansion is an issue, but in my experience with other equipment (turbines and compressors), thermal expansion rates are a very important consideration for the drive train.

Also, I know that in V type engines that are prepared for competition, the cylinders are honed with deck plates. Deck plates are torqued onto the block to allow the machinist to simulate the stresses normally induced into the cylinder wall by the head studs.

Just my 2 cents. Good luck.

[kenikh]

Originally Posted by AlfonsoR

I went with 993 studs and 964 nuts, based on Steve Wieners recommendation.

I think thermal expansion is an important part in making the engine last longer. Steel studs and material with similar expansion rates to steel, I think, induce unwanted stresses into the cylinder walls due to the difference in expansion rates of the steel stud versus the aluminum heads and cylinders.

While this thread does get a little bit ponderous near the end, everything regarding different studs, their thermal expansion properties, corrosion resistance, rockwell hardness, grain structure, thread pitch/count, thread finishing process, as well as myriad other things...are here:

http://forums.pelicanparts.com/911-engine-rebuilding-forum/482439-headstuds-would-you-use-these.html

[Geronimo '74]

That's a very informative thread indeed! a must read!