Head Studs

[sojahseh]

If I remove the heads from my 85 with 90K is it recommended that I go a few steps further and replace the head studs with new ones? Are there any others to consider, or is genuine the best bet?

I appreciate the feedback.

-matt

[500_19B]

Although seemingly not as frequent as with SC's, Carrera head studs do sometimes break. On my recent rebuild I used Supertec head studs which are phenomenal quality and not that much more than stock steel studs (assuming you would use new nuts and washers).

In your case I would definitely consider it.

[tom1394racing]

Standard practice for these engines is to replace the lower (exhaust) Dilivar studs with steel studs. Steel studs do not break in street motors.

[Henry Schmidt]

The 911SC had more head stud problems (IE: breaking) then any other Porsche engine.
They were the first production engine equipped with Dilivar and they only used them on the bottom row making the clamping force on the cylinder to head joint incredibly uneven.
Throw the Dilivar studs away and seek another solution. Of course I think Supertec studs are the best but I advise you to do your own research and come to a conclusion the fit your sensibilities including budget.

[Mark Henry]

I just ordered your studs from here and they are back-ordered?

[Henry Schmidt]

Originally Posted by Mark Henry

I just ordered your studs from here and they are back-ordered?

Every time there is a discussion about head studs on this forum, there is a rush on my studs. People hear the arguments for and against and many builders choose my studs. We don't even have studs for three engines we're building now.
For some reason, the supply of our material with certs is in short supply. Our studs will be available in about two weeks.

[sojahseh]

Do people consider the head studs to be single use? Or are they only replaced when broken?

[Mark Henry]

Originally Posted by Henry Schmidt

Every time there is a discussion about head studs on this forum, there is a rush on my studs. People hear the arguments for and against and many builders choose my studs. We don't even have studs for three engines we're building now.
For some reason, the supply of our material with certs is in short supply. Our studs will be available in about two weeks.

It's cool.
I was hoping to get it sent to my US buddy in time for hershey, but I'll just have to wait till he comes up to my place in June.

[yelcab1]

Originally Posted by Henry Schmidt

Every time there is a discussion about head studs on this forum, there is a rush on my studs. People hear the arguments for and against and many builders choose my studs. We don't even have studs for three engines we're building now.
For some reason, the supply of our material with certs is in short supply. Our studs will be available in about two weeks.

So is this a good problem or a bad problem for you Henry?

[safe]

I ordered a set of Henrys awesome studs too a few days ago, back ordered.

I'm a bit annoyed with Pelican for claiming to have 1 set in stock, when they don't....

[Speedy Squirrel]

If you are not going to reuse your lower studs I will by them. They are reusable and I think they are a better solution. PM me if you want to sell them.

[Lapkritis]

Yes, replace all. Plenty of decent replacement options.

[Henry Schmidt]

Originally Posted by Speedy Squirrel

If you are not going to reuse your lower studs I will by them. They are reusable and I think they are a better solution. PM me if you want to sell them.

I have a plethora of used Dilivar studs. Mostly early Dilivar.
I would not recommend that anyone use them ( in fact it's crazy) but I will sell as many as you want for $ 5/ea.

[Lapkritis]

Halves worth $2.50?

[Mark Henry]

Originally Posted by Lapkritis

Halves worth $2.50?

I'm sure Henry will toss in a few for free if you buy a set of old Dilivar studs.

[sojahseh]

Still up in the air. I am leaning toward reusing the ones in the block, provided they are still holding up.

First step for me is starting the teardown and inspect them further, see if I can make it to the goal of removing the heads without breaking any.

I'll post an update in a bit.

[tom1394racing]

At a minimum, you should replace your lower (exhaust) head studs with steel studs. The lower Dilivar studs ALWAYS break due to corrosion cracking. If yours are still in one piece, consider yourself lucky.

PM me if you are interested in a set of lower steel studs.

[Lapkritis]

Host has the lowers for $14ea in Steel by Canyon...

Pelican Parts - Automotive Parts and Accessories - Porsche & BMW

[Henry Schmidt]

With all the talk about cylinder expansion rates, I wonder if it ever makes sense to run dissimilar studs on the same engine?
The 78-83 experiment with dissimilar materials was abandon in 84 and never revisited by Porsche. Just like the engine builders in the real world, Porsche engineers learned something.

No matter what studs are chosen, they should all be the same. Now the only question is, are there studs that offer superior characteristics?

[chris_seven]

Originally Posted by Henry Schmidt

With all the talk about cylinder expansion rates, I wonder if it ever makes sense to run dissimilar studs on the same engine?
The 78-83 experiment with dissimilar materials was abandon in 84 and never revisited by Porsche. Just like the engine builders in the real world, Porsche engineers learned something.

No matter what studs are chosen, they should all be the same. Now the only question is, are there studs that offer superior characteristics?

Henry,

I absolutely agree - completely crackers and having been involved in hot gas turbine test stands for years I find the concept of mismatched expansion rates of studs bewildering.

There must be all sorts of ugly 'out of round' issues to worry about and it can't help the longevity of integrity of the CE Ring.