head studs on 81'sc

911 tweaks · 11-05-2006, 09:15 AM

Hey Guys!! Sorry for the old subject, but, please confirm what I have.
A little history on engine...81' stk 3L w/recon pistons & cyls...so I was told...engine has been sitting in shop for 5 yrs...so at least that long since any stud replmt would/could of been done!
All of the bottom studs are Black and magnetic(as the right side stud in picture is).
All of the top studs are metal(as left stud in picture is) EXCEPT, 1 stud on top is the pictured Black stud which is magnetic like the bottom ones & obviousley the steel studs.
I don't know the timing of what studs became avail, what their specific diffeences are/looked like...
Thanks for all of your help!
Bob

rlane · 11-05-2006, 04:08 PM

I am sure you have seen the long htreads on various head studs and I hope some of the really lnowledgeable members can give you details but it appears that in the prior rebuild all the exhaust side Dilavar studes were replaced as well as one on the intake side, probably with the epoxy coated steel studs. I have no clue about dates but have heard these referred to as 993 studs so that would date them to 90's

911 tweaks · 11-05-2006, 05:30 PM

thanks! I thought the epoxy coated studs were much later than that i.e.early 00-01'. OR, these were a hybrid kind of stud.

I guess if these are epoxy coateds steel studs, are they durable/long lasting studs??
Thanks Richard.

rlane · 11-05-2006, 05:59 PM

I am definitely not the expert on these, in the middle of reassembling my first engine rebuild (78SC) I opted for the ARP studs but probably should have gone with the Supertec studs. Wait for better opinions from the real experts on here to accurately date those epoxy coated studs

911 tweaks · 11-06-2006, 03:50 AM

Hello Herny!! Your garden of knowledge is being asked for a quick answer on the studs and how to tell em' apart from each other.
Thanks as always...Bob

mb911 · mb911's Garage

They are probably just steel that are coated with epoxy. I am curious as well. Hopefully when henry wakes up on the west coast we will have an answer

911 tweaks · 11-06-2006, 08:35 AM

Thanks Ben. I will wait a while for Henry to hopefully chime in.
Has anyone done a "chronology" of head stud evolution?
That would be a great ref to have here at Pelican. (it probably already exists but I did go through the posts from searchs and couldnt find anything conclusive...it is probably buried in a different subject which could be anyone's guess where...)
Hello Henry!! Help Henry...maybe I can get Henry to answer if I say that I am thinking of pulling the studs and buying Supertech studs...only kidding Henry...though I will buy them when I build a high output engine for sure...:-)

Walt Fricke · 11-06-2006, 10:00 AM

Tweeks

In about 1986 or 7 I pulled the top end off my 2.7 and had a shop install timecerts and what I thought were Dilivars (because that was what I asked for). Black epoxy coated studs. In the fullness of time that engine blew up when a valve fell into it and I pulled the black coated studs out before sending the case off to be welded. Later I learned about using a magnet. Lo and behold, those studs attracted a magnet, though not as strongly as some straight steel studs I had. But the for sure Dilivars I had accumulated by then did not attract the magnet. So I had been sold a set of fake Dilivars.

On occasion I have replaced a broken Dilivar (broken on removal, not in service) on one of my aluminum cased race motors with one of these black coated jobbies.

Not had a problem. Of course, this may be in line with the suggestions that one can with some safety run with one (or even a couple, if spread out) broken stud for quite some time on a street motor.

Anyway, if that motor were mine and my plan was to run it without a rebuild, I'd not fret about the black sheep. In fact, were I to rebuild it (especially if to stock specs) I'd be inclined to leave the studs alone. They aren't broken.

Of course, I don't build engines for others. If I guess wrong, I just pull mine out and deal with the problem on my own time without too much grumbling. And I can R&R my engines without worry, having done it more often than I'd really care to. So the idea of running an engine to see what happens to the studs doesn't cause angst.

Walt Fricke

911pcars · 11-06-2006, 10:20 AM

I believe the black expoxy-coated Dilavars were introduced around '84. I've got 24 of them in my 2.7 rebuild.

Sherwood

911 tweaks · 11-06-2006, 10:35 AM

Thanks Walt & Sherwood! For what its worth, when I place the magnet, the magnet is a round cylinder shaped magnet just like 1.5" worth of a wooden pencil, if you know what I mean...anyway, when I place the magnet on the left steel stud I feel the mag attraction...I then pull the magnet away and re-approach the area again this time touching the right stud i.e black stud and it pulls 95% as strong as the left steel side.

Think I have the fake studs that Walt is referring to?? Since they are some knid of steel, any idea who made them and maybe, as with any valve adjmt, just check the stud nuts to see if they are loose indicating a snapped stud...?
Thanks guys!! Bob

911pcars · 11-06-2006, 10:57 AM

It sounds like a faux Dilavar stud. According to B. Anderson, the fakes were marketed as Dilvar, Dilivar and just plain Dilavar fakes (but actually just steel). Your rebuilder probably recognized them as regular steel and installed them with the other steel studs.

My guess is that the steel in these fakes is nothing special and perhaps less than adequate. I would replace them with factory studs or whatever aftermarket studs you decide to use.

Sherwood

Henry Schmidt · Henry Schmidt's Garage

Did I hear someone calling me?

It sounds to me like you have encountered what some of the after market companies call "superstuds". They were and are sold by SSF, IMC and others as a Delivar replacement.
Although I have little experience with these studs may guess is that they are just fine. I would however try (forget that) I would get a set of studs that match. If you only have one odd ball stud replace it with a similar stud.
Otherwise if they are not Delivar they are probably fine.

911 tweaks · 11-06-2006, 11:45 AM

You have supereb hearing among other talents Henry!!

I thank you for solving the mystery. Soooo, I would have to remove the heads/cam towers to replace the 1 "black" top side stud...OR... leave well enough alone for the time being??

AND/OR also remove the towers/heads to take out all of the bottom studs which are these mysterious "black" studs??

just double checking on your suggestion & glad you have such good hearing!! Keep up the great work and help to us fellow Pelicans!! :-) Bob

Henry Schmidt · Henry Schmidt's Garage

If the engine is running I would leave it alone. When it comes time to take it apart, repalce the odd stud.