930 crank case replacement needed!

[simsalabim]

Just got more bad news about my ever growing list of engine teardown discoveries. My car is a 1981 sc.

After removing 1,2 and 3 cylinder heads, it looks like the rebuild done in 1997 (I just bought this, my first Porsche) replaced the head studs but re-bored the threads crooked on a couple! Too much material missing adjacent to the cylinders too so a re-bore looks way too risky, in fact, one of the cylinders has a small perforation in its wall about 1" from top opening. The crooked studs were actually bent in order to fit the reinstalled heads! One of them is now pulled through completely.

Not exactly what I was hoping for when I finally pulled the trigger on a car like this, but that's what I got and I have to deal with it. Yes, I did a P.P.I by a reputable PCA mechanic too...

Question now for anyone out there is what should I do now? Used case? Used engine? two month bender?

I would really appreciate some insight. BTW, I am in So. Arizona...

Thanks all,
Bill

[Steve@Rennsport]

Bill,

I'm very sorry to hear of your misfortune here. Its tough to spot these issues in the average PPI due to time and customer budgetary constraints. I've seen this problem before and I simply cringe when seeing the result of "shade-tree mechaniking".

I think the best way forward here is to either source a GOOD used SC/Turbo case or perhaps a decent complete 3.0 core engine for parts and sell off what you won't need when the job is completed & running.

I'd postpone the bender until its all running well once again and give you good cause for celebration.

[simsalabim]

Thanks Steve,

The hard part will be sourcing either a "good" case or the engine I imagine. I am new to this forum as well as these cars so I am open to any and all suggestions as to how to go about this.

By the way.... care to cringe?

[Raceboy]

Ahh, hurts my eyes to see such a damage on otherwise good case.

I may be totally wrong here but wouldn't heli-coil or timesert work in this case? or is it too little meat there?

[simsalabim]

Thanks R.B..

While open to all second, third and fourth opinions, my mechanic is pretty adamant about your "not enough meat" assumption. I would love to be pleasantly surprised but I am not holding my breath.

[Raceboy]

Ok, my opinion was purely based on the fact that 2.7 mag cases have equally small amount of meat between head stud and spigot but case-savers, tim-serts really work on those and aluminium is stronger than magnesium.

[ajwans]

Can you TIG it and then have it drilled and tapped straight? Ollies is in Arizona, they might be able to give you a second opinion.

andy

[Ronnie's.930]

You can see the area that "punched through" about an inch down in the cylinder "hole" . . . I, too, would look at getting that welded and machined (but Steve didn't mention that option so maybe it is not doable?) . . .

Like JimTweet, over in the 930 forum, would say: MFer, WTFer, SOB!!!!!!!!!!!!

[quattrorunner]

Originally Posted by Raceboy

Ahh, hurts my eyes to see such a damage on otherwise good case.

I may be totally wrong here but wouldn't heli-coil or timesert work in this case? or is it too little meat there?

Yes what about this steve? A combination of tig welding some additional material back and time cert or helicoil?

[Steve@Rennsport]

I didn't mention TIG welding (I've done that on rare, collectible cases such as RSR & 935) because the parent metal around the weld is changed and its not as reliable. I only do that for display engines such as the above. Remember, those are 1 million dollar cars with special cases that are NLA.

For anything you will USE, I'd strongly recommend getting another good used, unmolested case.

[simsalabim]

Thanks to all for responses. It really helps knowing there are folks out there who understand and want to help.

The tig thing was discussed and dismissed for the same reasons Steve pointed out. I want to restore and use this thing, then pass it on to another who will appreciate it... do NOT want to half-ass it once again (too much bad "car-ma" already... sorry).

I am still at a loss as to the best ways to seek out a good replacement case or even a core engine. Does anyone have any suggestions outside of this fine forum? PCA classifieds? Specialty machine shops?

Lastly, I know that the 911sc cases were changed slightly as the model ran it's course, mine is an 81 and the p/n's off the case (one side) reads 930.101.103.4R and the other is the same except a 104.4R. I understand this is simply a right and left side of case designation. I also understand that these same numbers can be seen on all sc cases throughout the years (78-83). My question: If they made changes to the cases, why did the p/n's stay the same? Should I look for a particular vintage case?

Thanks for sticking with me folks,
Bill

[Walt Fricke]

I'd start with the various Porsche dismantlers (aka junkyards). You could try "used Porsche parts" in a national search. You will find several who advertise in Panorama, the Porsche Club's magazine. Don't belong? Well, you should. Worth it. I don't know if Pano is available on line, at least to non-members. Any SC case will do fine. And you can post a want ad right here on Pelican on the for sale forum. Some of the guys who have a sort of sideline selling used parts read that.

Myself, I can't imagine why anyone would insert a 3.0 case. Unlike the magnesium cases, they don't need it. Maybe somehow threads were messed up removing the studs to replace them? But there you are.

I can't imagine a PPI catching this. Maybe if you used a borescope with a 90 degree mirror you might be able to examine these locations? But damaged studs and case spigots are simply not the kind of thing you expect on these motors. Leakdowns good, compression good, cams and rockers look good, all head studs are solid, what more can you expect?

[fastfredracing]

Porsche 911 3 0 SC Engine Case Block | eBay

There are a few on there right now, and I see them pop up frequently here on the classifieds . All is not lost

[simsalabim]

Thanks FFR..

Saw that one yesterday. Want to do my best to find a good one this time.

What have you seen as far as pricing in your experience?

Bill

[simsalabim]

Thanks for the advice and insight Walt (as always).

I did just join the PCA, so maybe I will tap their resources as well. So far I am having some success finding some old cases out there but I am trying to be as careful as possible this time (pricing and condition) and want to do as best as I can to find a "good one". Once bitten....

Trouble is, how can I be sure I am buying a good one?

Cheers

[yelcab1]

I have a very different opinion.

Buy a good used 3L engine from an SC, and replace yours with it.
THen part out your engine to recover some of the cost.

Quick, and you are no worse than before. But if you are a stickler for the devil you know, then buy a used case, measure it out, clean it, line hone it, and put the guts back.

[simsalabim]

Thanks Yelcab..

Yes, a new motor is a possibility, but at what cost? how find a sound one?

Prevailing wisdom seems to be leaning toward the devil we know philosophy but in the end, a crap-shoot is the game being played. Plus, there is the "numbers matching" thing which may (or may not) come into play some day.

[Walt Fricke]

I am dubious that numbers matching is ever going to mean much in the SC world. They are great cars, one of the best models ever (I have one, though it is a hermaphrodite which started as a 2.7, but is now full SC spec in all respects). But one which has been around the block many times is unlikely to fetch top $ 20 years from now, seems to me. Especially if you do what it was made to do - drive it, maybe autocross it, maybe DE it, and have a lot of fun.

And if your current damaged case has the requisite matching numbers, well you can keep it (won't fetch much as aluminum scrap), spend years talking with metalurgists about how best to repair it, and when you are getting the car into Amelia Island or Pebble Beach show condition, preparatory to Barrett-Jackson, you can build up an engine using the old case and on and on.

Some of the sellers of cases are people in the business and have reputations. Those with bad ones you can ferret out (check out MM if that comes your way). Those with good ones you can check, and they have something to protect. They can check the case out. Generally, it is believed that these cases, unless obviously damaged, should be fine. Are the bearing bores concentric and in spec? That's about all, really, because if they are, the case shouldn't be warped either.

You should be able to find a case which doesn't need line boring. If you do end up with one which does, you have Ollies nearby, and they can shave it and rebore to standard. You do not, repeat not, want to be dealing with oversize OD bearings - mucho dinero now, and when it is rebuilt again, and so on.

[simsalabim]

I hear you Walt, I would at least like to stay as original as possible if I have my druthers. You never know right?

Having said that, another member has offered to sell me a very nice 3.2 case that he states will work with all of my other engine parts (except the oil pump, which he can also provide.... its a turbo pump too, so better cooling as well?)

Any thoughts on this? I have been told that the end of the sc run (1983) saw the use of the 3.2 cases with the 3.0 motors before they updated the following year?

and the plot thickens....

[Walt Fricke]

Porsche has a history of using what is on hand. So sometimes the last of a run gets parts from the start of a new run, as with the 3.0 cases. The dies were worn out, the new ones were made, the dimensions are all the same, so why not use the 3.2 style cases on the last 3.0s?

Some 1974 2.7S cars came with the earlier S aluminum front caipers. Guess they had a bunch of those left over in the parts bin, so why not and leave the cast iron A calipers for later?

I like the Turbo oil pump - have one in one of my race motors. But in another motor, one I purchased, there sits just the standard SC/3.2 pump. I spun that motor up even higher (8,200), and it never had a lick of an oil pressure issue despite two 964 coolers through which all that oil had to be pumped by the scavange side. So for a street motor the Turbo pump is overkill. In fact, it will cost you some HP by increasing parasitic drag. But not enough to worry about as a practical matter. If the case is already clearanced for it, and comes with it and the shorter connecting tube to attach it to the intermediate shaft, go for it.

With cases, it used to be that guys looked for the casting numbers. The ultimate 2.4/2.7 case was the 7R case, which had better reinforcement than its predecessors. But that isn't true with the SC and 3.2 cases. All equally stout. Besides, no one purchases a case by part number. That is, unless you purchase one through a dealer brand new (does Porsche still have a stock of NOS 3.2 cases?). The part number cannot be found on the case, as is the case with most parts. All you get is the casting number. And a stamped serial number and model number.