The plan was only to seal up the SC Engine
 

Yes, It was the plan to seal the engine, since it was leaking like crazy. Long story short:
The engine is out, started disassemble, heads, cylinders are off. Besides 3 snapped dilavar head studs (which are out now, see post Here ). I found one bad piston, pics below.

http://muelhaupt.us/images/piston01.jpg

http://muelhaupt.us/images/piston02.jpg

The Cylinders look good to me, pics below.

http://muelhaupt.us/images/cyl01.jpg

http://muelhaupt.us/images/cyl02.jpg

Here are the options I'm thinking about.

1. Find a good used piston, get a set of new rings, reuse the rest of the pistons and cylinders.

2. Get a set of new JE pistons 9.5 and put it back together with the current cylinders.

The car is a Euro model.

Any input is apreciated

Thanks
Engelbert

The 78/79 SC uses the same piston across the line, euro or US, 93L7 Mahle and 95136 KS. These are readily available used, you need to know the deck height, the triangle with a 5 or 6 inside. and you have the other pistons to check weight against.
Bruce

Why does the top cylinder look like Nikasil and the bottom look gray like Alusil?

Probably because the top one is reflecting the (unseen) light source while the lower is reflecting the paper towel it's resting on.
regards,
Phil

Its been detonating,...hard.

Before you start the new engine, you need to figure out why it was doing that so you don't have an "encore performance".

Too much ignition timing, insufficient octane fuel, lean fuel mixtures, are just a few causes to look into.

What effect would the 3 broken head studs have on the Ps & Cs?

You don't want to use J&E pistions unless you are switching to carbs or EFI. The CIS needs the funny shaped dome for swirling the air/fuel mixture. No aftermarket company makes a piston like that.

Good news is that you ought to get a decent used stock piston pretty inexpensively. Think of all those guys who switched to carbs and bought J&Es. Just have to match it up with what you have, and be sure you get the flavor you have: Alusil or Nikasil.

And, of course, figure out why this happened, and on just that one piston, too. Bad injector?

Here is some background about this car.

According to the PO it was sitting in a barn for 10 year. He put in a new gas tank and fuel pump, plus some of the fuel lines, it was all gunked up. He drove the car for a little wile and lost interest and patient to work on it. I rescued the car and took it home drove it a little and it was running not bad.

Since it was leaking like crazy I parked it and decided to take the engine out and seal it.

Here is something what could have over heated cyl # 3, the one with the bad piston. A mouse must have lived in there for a wile, and I don't know many miles the PO did like that.

Would this make sense ?

When I disassembled the engine one head stud of #1 was already snapped, just hanging loose.
The headstuds on #3 were OK.


http://muelhaupt.us/images/motorraus11.jpg

http://muelhaupt.us/images/motorraus12.jpg

Thanks for the info on the JE pistons !
Engelbert

Yes, that makes perfect sense. Rodents still carry the plague.
regards,
Phil

Where did the rest of pictured piston ring land part(s) go - if the cylinder looked fine? Did it break off on dis-assembly?

Te piece was still hanging between the piston rings. I just noticed it when I had on the workbench to take the rings out and clean.

Day--ja--vuuuuu!
 

Gee, that looks familiar! You are not alone...

http://forums.pelicanparts.com/uploa...1131083118.jpghttp://forums.pelicanparts.com/uploa...1131083152.jpg

Full story here:
http://forums.pelicanparts.com/911-engine-rebuilding-forum/248145-pieces-came-tumblen-down.html

Here is my thread on finding a replacement single piston and what to look out for when buying one:

http://forums.pelicanparts.com/911-engine-rebuilding-forum/388967-differences-diameter-groups-pistons-cyls.html

Enjoy!

-Michael

Lots of us successfully use JE pistons with CIS. While I understand what you are saying with regard to the shape of the dome, it doesn't seem to be an issue. If it is then there needs to be some sort of technical data to support that claim. Not trying to be argumentative - just trying to get to the facts. I'd love to know more for future rebuilds.

I also believe that JE has custom pistons available that are better suited for CIS than their off the shelf pistons. I bought mine through EBS and they were custom built - EBS supplied specs to JE.

Granted, I would have stuck with Mahle if my budget had allowed (but more so because of the expansion rates and not because of dome shape).