911 SC head stud replacement only
 

All I have a an 81 SC with at least one broken head stud. I have limited funds and put limited miles on the car. ~5K a year. The car has ~155K on it now and uses ~ 1 quart per 900 miles. Leak down numbers on all cylinders are between 2-4% on all cylinders which surpassed me and the mechanic I took it to to perform the test. He expect higher numbers based on mileage more than the stud issue. Anyway given that the engine seems to be in good shape and I do not have unlimited funds I was thinking of just replacing the studs with supertec studs and putting it all back together again. No head job no bottom end etc. If I got 30K miles out of it this way that would represent over 6 years of driving at the current rate of miles per year. By then (kids out of private school) there will be funds for a more in-depth engine re build project. Are there any strong objections to this plan? The only other upgrade I would do is replace the 30 year old heat exchangers with SSIs. and a new two in one out muffler.

Also if I do go the minimal invasive route what parts should I have on hand outside of the studs and the normal triangle of oil leaks gasket for the breather and oil sensor switch.

If your in the your crazy camp and think I should do a top end what additional parts should I have on hand? Assume the heads are going out to a pro.

If your engine is all fine except for the studs, then just doing the studs is fine. They can be very difficult to get out though. Two of mine had broken flush with the case so I ended up splitting the crankcase to get them removed by a professional. I would also recommend changing the front and rear crankshaft seals, the oil pressure switch, engine breather gasket and thermostat O ring. All of these parts are relatively cheap. A leak check for the valves by filling the combustion chamber area with paraffin might be a good idea to see if all valves are seating properly. Grinding the valves in and replacing the stem seals is not difficult or costly but it would mean separating the heads from the Cam box which could otherwise be avoided. The oil return tube O rings should also be replaced. If there are any obviously leaking case through bolts, you could replace the O rings if you did only one bolt at a time.

Hope this is helpful!!

If you are on a limited budget, a set of (12) replacement OEM steel studs to replace the lower Dilivar studs will be adequate.

For the amount of work involved to remove and reassemble the top end, it would be tough for me to resist doing a valve job on a 155k mi. motor if the heads are sitting there on my work bench....

Forget the muffler and ssi's unless you face serious issues there. A few holes in the ssi's (not the actual manifolds) can be welded shut and will last another 40k miles. Use the money on the top end.

The last thing I would be spending money on would be on custom exhaust when a valve job is called for at half the price of custom exhaust.
You can buy used heat boxes right here for cents on the dollar if youre rusted through..
Bruce

Defiantly a valve job over SSI at those mileage. I would always check valve guide wear at any mileage if the heads are off.

Getting the parts clean.......
 

The biggest problem that I see will be getting the parts clean enough with the block still assembled. Also, you will have to pull the cylinders/piston assemblies in order to be able to put heat on the block to pull the dilivar studs. You will need to mark each cylinder for location and do your best to remove them as assemblies without pulling the pistons out of the cylinders. The piston pin clips can be difficult to remove due to limited access room. Just some things to think about! Good luck with your project!

I cleaned my engine as a long block thoroughly before disassembly when I did my top end rebuild.
I have never understood the thought process behind "don't remove piston" theory.

911 SC head stud replacement only
 

Broken studs usually cause head sealing surface problems unless you catch it early. You can check the guides but again if you let them go too long it beats the hell out of the seats and can make truing them up a real task.

Thanks all for the great advice. I will look around for some good used heat exchangers. Mine are totally rusted through. No heat at all in the car which isn't fun. As far as Divlar vs Supertec I thought that was a a false economy. Its less than 500 bucks difference to replace them all and then I never have to worry about the issue again. I guess from my point of view the studs are a foundational part of the engine and one should not cut corners there . . .

As notes by an earlier poster, why do teh cylinders have to stay in the jugs?

Nick

The point being that you will gain nothing over using the stock steel studs (NOT Dilivar) vs. Supertec in an aluminum case in a road car. Save the $$ and fix something else. You need 12 of 911-101-172-00-M260 if i'm not mistaken, $138 + shipping.