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-   911 Engine Rebuilding Forum (http://forums.pelicanparts.com/911-engine-rebuilding-forum/)
-   -   Mission impossible: (http://forums.pelicanparts.com/911-engine-rebuilding-forum/861249-mission-impossible.html)

JmuRiz 04-24-2015 10:12 AM
Quote:
Originally Posted by Henry Schmidt (Post 8591838)
We get a lot of calls but it could be....
It was in a 914/6 GT. Does that ring a bell, Mr. Bell ?
Wow a 914/6 GT with that engine...that would be a dream car of mine!

I'll watch this build!!!

Henry Schmidt 04-29-2015 01:06 PM
Case is off to EDM the broken studs.

http://forums.pelicanparts.com/uploa...1430341438.jpg
http://forums.pelicanparts.com/uploa...1430341466.jpg

Heads are clean and inspected with one head showing a substantial crack.
Weld or replace is the dilemma for the owner. I can fix it but should we?
If the engine was going racing rather than in a spirited street car I'd go with replacing.


http://forums.pelicanparts.com/uploa...1430341581.jpg

Lapkritis 04-30-2015 07:49 AM
Looks like someone had at the head with a dremel around the other valve...

Spooky crack for sure. Fortunate that valve seat didn't drop out.

confused 05-02-2015 09:53 AM
I saw all these parts on a cart yesterday and had to do a double take. A little beat up but repairable. Cool stuff for sure. Thanks for lunch Henry.

Henry Schmidt 05-04-2015 08:44 AM
Quote:
Originally Posted by confused (Post 8605026)
I saw all these parts on a cart yesterday and had to do a double take. A little beat up but repairable. Cool stuff for sure. Thanks for lunch Henry.
Next time, lunch is on you....lol

MBAtarga 05-04-2015 04:16 PM
Quote:
Originally Posted by Henry Schmidt (Post 8591006)
Here's what we found.
Good:
Bosche twin plug
Factory oil filter console
Factory small diameter fan and housing
RSR crank
late 3.0 RSR case with 86mm stud spacing
5 RSR twin plug heads (12m spark plugs)
98 mm Malhe pistons and cylinders
Polished steel rods
Aluminum cooling tin
Aluminum 908 style (SC) oil pump

The Bad:
One head made form production head.
One cylinder modified to work around damage
Three journal cam towers (bad choice with heads)
Case repair
Two different length valves
Stock case through bolts :(
No MFI drive

Ugly:
Because the cam towers are 47 mm (three journal) the base circle on cams is designed for 2.7 valves (longer than 3.0) That meant lash caps on intake valves.
Exhaust valves are 43 mm made from 2.7 (46mm) intakes, creative but....yikes
Old school fiberglass coated Dilivar head studs (two broken)
Mixed and matched rockers, some forged some cast.
Poor quality solid tensioners
Strange spacers on the cylinders??
Maybe the company we shall refer to as MM had their fingers in this at one time! :D

porschetub 05-05-2015 02:09 AM
Quote:
Originally Posted by MBAtarga (Post 8608160)
Maybe the company we shall refer to as MM had their fingers in this at one time! :D
LOL,it looks that way,has all there trademarks:confused:

Henry Schmidt 05-10-2015 11:35 AM
Quote:
Originally Posted by MBAtarga (Post 8608160)
Maybe the company we shall refer to as MM had their fingers in this at one time! :D
Quote:
Originally Posted by porschetub (Post 8608691)
LOL,it looks that way,has all there trademarks:confused:
Having had quite a bit of experience with the rescue and rebuild of a number of the MM engine projects, I would guess this was a DIY guy that had some ideas that a professional would never try. It really feels like "racing on a shoestring".

KTL 05-11-2015 06:44 AM
RE the poor quality tensioners, they look like something forum member stormcrow recently showed us on his engine. They looked odd to me & I commented on them. He mentioned they are somehow spring-supported inside the tensioner body. Weird.

http://forums.pelicanparts.com/porsche-911-technical-forum/860674-chain-tensioner-video.html

Fiberglass sleeved studs?! Is that similar to the fire sleeving typically used on hoses to protect them from heat?

Henry Schmidt 05-11-2015 08:52 AM
The tensioners (poor quality) pictured do not have any spring mechanism. They are solid.
This was a very common practice back in the 70s and 80s. When adjusted properly (slightly loose when cold) they offer reliable performance. The only problem with them is that they need to be adjusted properly. If they are too tight, engine components wear prematurely. If adjusted too loose the engine will rattle at idle when cold, and if they are very loose you could encounter cam timing changes.
The good part, if adjusted regularly they will never fail. All hydraulic type tensiones can fail.
The bad part, you have to adjust them. In a street car that is generally around 15K miles. In a race engine, around the time of a freshin-up.

Henry Schmidt 05-12-2015 06:07 AM
Quote:
Originally Posted by KTL (Post 8617865)
Fiberglass sleeved studs?! Is that similar to the fire sleeving typically used on hoses to protect them from heat?
In the early days of Porsche racing, the engineers developed the material we call Dilivar and immediately encountered difficulties with the product. They like the expansion properties but the failure rate was unacceptable. In an attempt to keep them (Dilivar studs) alive they covered them with fiberglass shielding.
Later race engines did away with the non sense until the engineers revived Dilivar for another round of disaster, only this time in street engines.

Flieger 05-12-2015 06:41 AM
I thought the fiberglass was meant as thermal insulation on the steel studs for the prototype cars (by which I mean 917, etc.), at least that is what I thought Fere mentioned in one of his books. Didn't the prototypes use the fiberglass on only the exhaust side to insulate them from the cooling air and help the steel expand more?

Dpmulvan 05-12-2015 06:43 AM
When I pulled my 1980sc apart every dilivar stud was broken or hanging by a thread. Don't know how porsche could let this bs go on.

Turbo_pro 05-12-2015 08:01 AM
Quote:
Originally Posted by Flieger (Post 8619661)
I thought the fiberglass was meant as thermal insulation on the steel studs for the prototype cars (by which I mean 917, etc.), at least that is what I thought Fere mentioned in one of his books. Didn't the prototypes use the fiberglass on only the exhaust side to insulate them from the cooling air and help the steel expand more?
You could be correct but I have never seen fiberglass shielding on anything except Dilivar.
Even going back to the four cam, 547/1 days. Of course I've only built a couple so anything is possible.

Trackrash 05-12-2015 10:00 AM
Another stud question
 
Are all the "original" steel head studs interchangeable? I have a motor that has what appears to be three different types of studs.

It is a '78 SC motor. Someone had replace the lower divilar studs on one side with steel studs that are painted black. I recently bought some steel studs of unknown vintage to use to replace the divilars on the other side. They look slightly different than the upper studs on my motor.

Is it OK to mix and match?

Henry Schmidt 05-12-2015 10:10 AM
Quote:
Originally Posted by Turbo_pro (Post 8619768)
You could be correct but I have never seen fiberglass shielding on anything except Dilivar.
Even going back to the four cam, 547/1 days. Of course I've only built a couple so anything is possible.
I've known you for ten years and had no idea you played with 4 cam engines.
I'm guessing as an owner not a builder?

Henry Schmidt 05-12-2015 10:17 AM
Quote:
Originally Posted by Trackrash (Post 8619899)
Are all the "original" steel head studs interchangeable? I have a motor that has what appears to be three different types of studs.

It is a '78 SC motor. Someone had replace the lower divilar studs on one side with steel studs that are painted black. I recently bought some steel studs of unknown vintage to use to replace the divilars on the other side. They look slightly different than the upper studs on my motor.

Is it OK to mix and match?
The painted studs are probably Super Studs. They were supposedly a Dilivar replacement sold by SSF and other wholesalers.
I would recommend using the same studs on the entire engine. Of course I recommend Supertec head studs but for your application, stock steel studs will suffice. We sell a reconditioned set of stock steel studs, washers and Allen head nuts in a set for $ 250. We also throw in the chain rail bolts.

http://forums.pelicanparts.com/uploa...1431454600.jpg

KTL 05-12-2015 12:20 PM
Sorry to start a stud shyt storm by asking about the fiberglass! Porsche sure has some sort of allegiance to that dilivar stuff. They've tried so many variations of the stud "cosmetics" to keep on using it.

Henry Schmidt 05-12-2015 12:25 PM
Quote:
Originally Posted by KTL (Post 8620116)
Sorry to start a stud shyt storm by asking about the fiberglass! Porsche sure has some sort of allegiance to that dilivar stuff. They've tried so many variations of the stud "cosmetics" to keep on using it.
No worries, I love talking about head studs. Every time there's a discussion my sales go through the roof.
The good part is that people end up with a quality product in their engines.

Henry Schmidt 06-09-2015 07:02 AM
The head was saved....yeh!!!
Now on with the rest of the project.

http://forums.pelicanparts.com/uploa...1433861836.jpg
http://forums.pelicanparts.com/uploa...1433861868.jpg
http://forums.pelicanparts.com/uploa...1433861879.jpg
http://forums.pelicanparts.com/uploa...1433861890.jpg
http://forums.pelicanparts.com/uploa...1433861900.jpg


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