This is my first 911 engine rebuild! An 188hp Euro SC Cr.8,6:1I torred down the engine in spring 2006, due to 6 broken head studs, and it ended up with following when the engine first was appart :
First of all, several hours where spend on Pelicanparts. com/forum, to discuss many isues arround the engine, as which parts to use, and where to get them for reasonably money.
There are many aftermarket parts, OEM parts, and not to forget many fancy racing parts, as
high tensile head studs, etc., so i realy needed to sort out! because as you know, your eys are ready to by everything!
Instead of buying very expensive head studs from ARP, Raceware or Supertech performance, i bought 12 std. 993 Dilavar studs from a dealer in Germany. Not many in the forum agree in this, because the Dilavar studs has been claimed for many broken headstuds isues since the midt 70's
This headstud decision, was taken because i discovered that the racing studs needs retorque
I do not want to retorque any head studs when this is not necesarry with the factory studs.
What is the worse thing : A broken headstud, or a lose one ??
To my luck, i found that the cylinders was of the Mahle nicasil type - this means that you can install new rings in them, and they will go for many km. again, because the nicasil(Nickel-Silicium carbide) coating is so hard that most of the wear is on the rings, and the cylinders was not very unround, as you typical see on cast iron cylinders. I discussed with serveral people in the forum - to hone them or not ? many divided opinions on that ! Talked to Charles Navaro at LN Engineering - Ilinois, he told me that they could be cleaned with a scotch brite in soap water, and this should bee enough.. I tried this soulution, and the car have now done arround 4000 km since feb. 07 , ond there is no problems with too much use of engine oil.
So what kind of liquid gasket to use ?? Here there was also realy many opinions on that! many means the Loctite 574 as used on the factory in Stuttgart, are maby not the best choise, because you will sooner or later get problems with oil leaks. many suggested to use the Yamabond (OE Yamaha liquid gasket) for the case half's (now caled Threebond 1104)
Reason why i used the Loctite 574:
- Designed to be washed out of the oil galery where oil galery are crossing mating surfaces.
- To prevent gasket rests to be catched in the small jets for downside piston cooling.
- Used by the factory.
New Washers for the case trough bolts where made as i found huge difference/ bad surface quality on the factory ones. The counter sink from the back side where made with so big tolerance, that some of the O- rings where splashing out. I made some tests with different counter sink size, and made new ones with even better surface quality than the factory part.
Cleaning:
Wayne Demsey from Pelicanparts, writes in his book that the cleaning isue are at least as important as which type of gasket you use, and i agree in this ! I cleaned all the parts carefully in the recomended Isopropylalcohol, and inspected all edges/mating surfaces for scratces and burrs. After the 4000 km now, there are still no oil leaks.
Summer 2008:
After around 20000 km. i discovered a minor leak from the left downside valve cover, but no other leaks or sweating gaskets so far. On earlier rebuilds on other engine types, i often used Hylomar on thin paper gaskets, but in this case all gaskets where fitted dry, except from the use of Curil T on some O-rings. The only difference this time is the final cleaning process, as mentioned above with Isopropyl Alcohol. IT WORKS !
The finished project Janury 2007:
A couple of changes i would like to do on my car / engine in the future could be following:
- Change the CIS. manifold with a Carerra 3,2 or a 964 Plastic manifold.
- New Megasquirt programable engine management system.
- Change the Brake system to : 964 RS front disc's/calipers on either OE 930 hubs or specialy
made CNC billet 7075 hubs. Rear: 930 disc's with modyfied 993 rear 30/34 calipers, but
here i'm planing to design a copy of the inner caliper half's in Pro Engineer (3D design program) , so they will get the correct bolt spacing to fit SC rear trailing arms. I do not like the method where calipers are modifyed by drilling new holes, to get the correct center distance between the mounting holes to get them fit to the trailing arms.
Example where new holes are drilled, to fit 3" trailing arms.
