Which Head Studs Do I Want?

[Paulporsche]

Well. while doing a "While I'm in there" valve adjustment during my new trans/ clutch installation, we uncovered a broken exhaust head stud. When the engine was rebuilt (about 1991) the PO had Dilivar studs installed in the bottom, which was typical then. The rebuild/enlargement has about 80000 mi on it.

I'm going to replace them w/ steel, which is what are on the top. In other threads, I've read about Raceware, ARP, Supertec and steel 993 studs.

The car is a daily driver w/ minimal track time, and it's likely that pattern will continue as long as I am driving, which would average about 5000 mi/yr.

I have some questions:

1 Which of the above brands of stud should I get? Or is there some other? Is plain steel, epoxy coating or powder coating preferred?

2 W/ only 80000 mi, should I be doing any other "While I'm in there" internal engine stuff?

[fintstone]

I like the Supertec studs. Unlike the others, I have never seen a post where they failed.

[adomakin]

I went with supertec.

[Driver8]

Here is a vote for Raceware. Had two 2.7 engine rebuilt both with Raceware and never had a problem.

[Noel]

Mine was rebuilt with 993 stuts about seven years ago.

[JeremyD]

Well, I went with Supertech - and can attest to their quality. As far as Raceware goes, I was talking to my wrench the other day and he told me he has two engines where Raceware studs had broken in the past fifty or so engines he has rebuilt - and when he rebuilds anything - the only studs he puts in are the 993 TT studs. He told me - in the few hundered engines he has done - he hasn;t had a broken stud in one of them.

[Superman]

I used plain ol' OEM steel studs. With an aluminum case, that's all you need and they don't break. I'd be happy using used ones. They're cheap, new or used.

[Rot 911]

What Supe said. Save your money for other things.

[Paulporsche]

Thanks, everyone. What w/ the new trans, clutch, flywheel, pressure plate, release and pilot bearings, half shafts, rear shocks, valve adjust, valve covers, fuel, air and oil filters, oil, trans fluid, and now, 12 new lower studs, my head's spinning!

[Grady Clay]

Paul,

While the heads are off, do a proper inspection and valve job. Even if they absolutely don’t need it, it will regain some performance slowly lost over 80K miles.

On general principles I would replace the exhaust studs. It is easy to extract a broken stud when you have the head in your hand.

What are the pistons & cylinders? Do you plan on new rings?

Best,
Grady

[Henry Schmidt]

I was a Raceware dealer and as such built most of our engines with them.
While installing the RW studs we started to notice an inconsistency in the threads. Some threads were better than others.
While rebuilding a 935 factory engine I found a set of studs that truly impressed me so I had the material analyzed and decided the have some studs made.
I thought long and hard to see if I could make them better not just copy what I found.
The net result was doing what all engineers would recommend.
Put a coarse thread in the case and a fine thread where the nut is torqued.
In every high performance application I have ever seen where you had a stud in aluminum / magnesium the aluminum end was coarse thread and the nut end was fine thread.
Examples: Hewland gear box, Rolls Royce heads, continental air craft heads, Donavan drag engines and the list goes on.
Porsche uses the same thread to save cost.

I asked ARP to make my studs for me but they would not do it stating that they already made Porsche head studs.
Funny thing is that there new head studs are now made of a similar material to mine.
I started making my own studs because no one else would.
The process is a tedious one. We start with bar stock cut to the right length. Next we grind each end to a different size. Then different threads are rolled on each end. Next the center is ground to remove the step. Then they are heat treated and Rockwell tested. It cost more to make my studs than any other stud on the market but we believe it's worth it. Now they are for sale to the general public and you can get them right here on Pelican Parts.
BTW: my studs have a life time warranty and we have never had to replace one. Oh I take that back, we did send one out to someone who lost one, at no charge of course.

Anyway that's my story and I'm sticking to it.

[Paulporsche]

Thanks again, guys.

Grady, the P&C are either 95 or 98mm Mahle, as the engine is a 3.2 long stroke on a 3.0 block, w/ a 10:1 CR and set up for twin plug, although I am only using single plugs.