So what percentage of SCs get broken headstuds
 

Serious question -lots of examples on here and its a common problem. But is it that all the owners with the problem post on here.

Can anyone estimate the percentage of cars to which it happens?

There are three kinds of SCs. Those that have broken head studs, those that will have broken head studs, and those whose smart owners replaced the head studs.

Isn't the issue more common with the 2.7 rather than the 3.0?

110%

18.4%

Even the newest SC is now 30 years old. What MREID said is dead solid perfect.

except for a few....30 years old, original studs all in place and recently retorqued at 227 k miles.
I do agree that they will not last ad infinitum but I'll let you know in another 50k or so.

probably tempting fate here but i have 117k on my 83 and all are original, re-torqued at about 110k.

That's pulled studs on the mag 2.7...as in pulled out of the casing. The dilivar studs on some 3.0's break...usually in cars that have been in wet climates and driven on short trips (not fully warm) then garage queened allowing for corrosion to set in on the exhaust studs. What I've been told anyway by a few local shop owners as to the breakage.

Presence of Dilavar head studs........
 

Good to hear that some SC engines have lasted this long with the original head studs (Dilavar). Incidentally, some new owners never realize that they have already steel exhaust cylinder head studs in place. One way to determine the type of cylinder head studs you have is do a magnet test. Dilavar studs are non-magnetic. I've seen SC engines that were supposed to be 'untouched' yet had steel exhaust head studs already. So you be the judge.

Tony

Thanks for the clarification. SmileWavy

The problem is different. On the 2.7 the head studs strip out of the magnesium case which is more involved to repair. On the 3.0 the head studs snap off, usually on the exhaust side (not that that's easier to repair, but less involved on the case side).

What I don't know is whether something changed on the early Carreras w/r to head studs. Is it just that SC's are older and the problem hasn't hit the Carrera's yet?

If most equals some then you are spot on. Dilavar was introduced in 1976.

Exhaust studs do not shear - they twist off. Dilavar studs get corrosion pits in them and heat cycling causes them to shear across the bolt diameter.

unopened and all original, know 25 years of the 30 history (same mechanic) and the magnet wouldn't stick. Knock wood, throw some chicken bones...

[QUOTE=boyt911sc;7246625. Incidentally, some new owners never realize that they have already steel exhaust cylinder head studs in place. One way to determine the type of cylinder head studs you have is do a magnet test. Dilavar studs are non-magnetic. I've seen SC engines that were supposed to be 'untouched' yet had steel exhaust head studs already. So you be the judge.

Tony[/QUOTE]

If I remember correctly SCs only had 1/2 dilivar studs(can,t remember if upper or lowers. Turbos were all dilivar

Have had 3 seperate 3.0s.....one snapped two lower studs. So in my case, 33.3%.....

My 83 sc had 4 broken at 87K miles!

It's just something you have to deal with, and I would recomend that you think about possibly replacing the lowers every time the motor is pulled out if it has been more than 80K miles.

Did it fit the low miles garage queen scenario?
BTW, when I finally drop the eng it'll get a full rebuild but my leakdown tells me that might be awhile if everything else holds tight.

I had mine done after returning from Desert Storm. The car sat idle for ~11 mos and did not take too kindly to running after I returned. So, in 1992 I did head studs at ~74K. The car's an '83 and I'd used it as a daily driver (excepting deployments) until then. I currently have 126K on it.

At 140K I found 2 broken head studs. Replaced all of them during a complete rebuild.