Is there any new knowledge about Mild Steel Head Studs
 

Hey everybody,

I'm currently rebuilding my '73 911t engine (close to stock). According to Wayne's book it is okay to reuse the mild steel head studs. I had mine replated but wanted to ask if there is any new knowledge about failure rates.

replace or ruse?

thanks for your input!

I presume this is a 2.4L MFI engine?

Your studs are not a mild steel. They are an alloy steel. Mild steel is not strong enough to be used as a head stud.

In theory, they can be reused since they are not a torque to yield fastener. In practice, there are a lot of things that can happen in 45 years.

Fatigue - this would be related to mileage and use
Corrosion - Exposure to salt and/or water
Damage - In removal damage can occur due to the use of gripping tools being used on the shank, or excessive heat being used to get them out of the case

Due to these factors, the critical roll they play in the assembly, and the difficulty in correcting a failure, most people would opt for replacement.

I've generally heard that the factory steel head studs are pretty durable. In fact, aren't failures pretty rare?

Not saying there aren't good upgrades available.

Factory studs are very durable. Don’t use re-plated head studs.

^^^this^^^

Plating can cause hydrogen embrittlement.

Yes, factory steel studs (I am unsure of the exact material composition) are very reliable in stock and mildly modified motors. I would challenge anyone to prove, with facts, other wise.

That said, there is a need and market for upgraded studs for higher performance builds. Higher CR, turbo etc builds.

I will leave that discussion to what is the best one to use to the archives and those that will post on this thread... :) What I can tell you is we have used factory steel on stock or mildly modified motors and ARP on other higher performance and turbo builds. No issues ever.

Now, that does not mean others have not had issues, or have a differing opinion. Every motor is unique. I am just relating our experience.

That said. I am intrigued by Supertech studs, and have committed to Henry that our next hi performance build will use them so we can get a sample set into our data.

Cheers

Mild steel is a ferrous metal made from iron and carbon. It is a low-priced material with properties that are suitable for most general engineering applications. Low carbon mild steel has good magnetic properties due to its high iron content, it is therefore defined as being ‘ferromagnetic’. MyLowesLife

I think you will find that most aftermarket studs for these engines are made from 17-4 as it is superior in its ability to resist corrosion, and for its high strength.

I'm a huge stick'ler for application and use. An engine is the sum of its parts and the heads studs serve a huge purpose in these engines as in any engine. Holding the head clamp tight without leaks should never be under estimated. This is why we use 17-4 in our studs, use certain thread classes between the case and stud, stud and nut, different materials between the nut and stud, a sealing system along with in some circumstances, a special head washer.

Assembly is also extremely important. How you go about installing the studs, what tightening process you use, are both very important. Consider everything.

A great stud with poor assembly is useless.