NineMeister

So, what happens when the oil feed pipes get blocked? It costs you a pair of cams and a set of cam followers:

Jacke2c

What is your favorite detergent to wash parts?

In your parts sink... I just finished buying one and find hundreds of opinions ... most against water soluble, some for... What is your opinion... mine warms the solution to 100 degree F

HiWind

awesome thread Colin! thanks again for your carefully compiled info and great pics.

NineMeister

None are perfect. The solvent wash is (was?) the most common and worked well, aside from the smell, the fire danger and the need to protect yourself from the stuff. Solvent is also fairly good at removing the excess silicone sealant since it swells up. Petrol will do the same but of course is not as safe.

The hot water wash tanks with strong detergent are also reasonably efficient and a more environmentally safe solution (apparently). Trouble with this is the need for constant heating and hence electricity usage. Same goes for the large dishwasher style tanks which are usually hotter still.

The other type which I am currently investigating is a bacterial wash, using a specific strain of carbohydrate hungry microbes to eat away any carbon or oil when you leave the parts in the tank overnight. This micro-system needs to be maintained at a lower temperature than the hot and of course does not involve labour to clean.

Bottom line: if it works for you, that's fine.

NineMeister

OK, so moving up to cylinder heads now. Here are a couple of shots of a head from that 2.7 engine which, if you recall, "had been recently rebuilt and just needs setting up on the dyno".

We did not need to measure the valve guide wear.

As for the seats, clearly someone had gone overboard with the seat cutter when fitting hardened valve seats. Look how much that intake valve is shrouded by the counterbore in the head. All the heads were scrap. Morale of the story is to pick your machine shop carefully.

NineMeister

Just found these photos of Ninemeister engine builder Mark using the foam-dab technique to apply Loctite 574 to the camshaft carriers prior to assembling the heads.

C4inLA

Fascinating... Can cam housing be attached to heads at workbench or lots of prefitting on block and cylinders?

Jacke2c

The first 911 engine I built was euro spec 3.0 1979 engine. Great engine and did everything right EXCEPT I did not put any sealant between the camshaft carriers and the heads. I had about a drop of oil per day on the floor on only one side of the engine. One side was dry, the other would always have a drop waiting to fall...especially when it was hot. It wasn't until about a month later that I had discovered my mistake not very lightly coating with sealant those two parts. Sad to say, I learned to live with it. It takes very little to seal some of these surfaces. One of the reasons I love Porsche engines is the build tolerances. I worked my way through my Ph.D. rebuilding K-series 900hp continuous duty Cummins all summer for earthmoving scrappers. Lots of small and big block racing chevy's, but nothing is as intricate, well designed, and as reliable as a Mezger engine.

Clay.0

Great thread. Lots of good info.

NineMeister

Yup, that's the plan. Far easier to build the assembly and fit all at once than attempt to do it one at a time on the engine.

Technically you could also fit the cams and followers, however we prefer to do these with the cam carrier on the engine to avoid the possibility of valves hitting pistons.

John McM

Colin, what purpose does the oil passage cut into the inside of the case serve? It seems to lead nowhere. Mine was blocked with 574.

NineMeister

Good question John. It's an oil drain groove. The 911 through-bolt holes are part of the oil supply around the engine, taking oil from the main gallery, through the holes and up to the piston squirters. Hence there is oil pressure running through them which is contained by the seals at each end. For all the other holes there is consequence of a leak at the centre joint in that the oil simply leaks down into the sump. In the case of that front hole, if that leaked it could pass to the outside of the case, hence Porsche add a pressure relief groove to return any escaping oil back into the case where it can do no harm. Ironically when this relief slot is full of sealant the engine is more likely to leak at that point....

John McM

Thanks Colin. You are the first person to answer that question. A number of other sealant threads show pics of that gallery fully covered.

I love the evolution of the 911 engine. I will have to go off piste with the dry nose bearing suggestion though as it was installed that way by my rebuilder but leaked like a sieve.

NineMeister

The o-ring should be greased, not dry. Furthermore there is an oil drain groove in the #8 bearing, hence the same rules apply. In all the years of building engines this way we have never had a #8 bearing leak, so I'm guessing your builder compromised the original o-ring or that there is a heavy scratch in the bore or groove where the o-ring locates.

JasonAndreas

Drawings of the relief groove have been in nearly every 911 workshop manual going back to 1972 but I don't think it was until the 996TT that they eventually warned to, "Check the relief groove in the area of the main bearing no. 7 for foreign objects, e.g. silicone residue and clean if necessary" I think because they switched from Loctite 574 to Drei Bond 1209 for sealing the case?