1983 SC Targa Mechanical Restoration

[roadster49]

I am a rookie rebuilding my SC 3.0 l engine. It is torn down and will begin the rebuilding process in the next few weeks. I bought the car knowing it needed work. the odometer says 130K miles but does not work. When I adjusted the valves I found the broken stud.


In addition to that one there were 2 more on the other bank. I was able to remove all the broken studs. I also found the oil thermostat broken with the bottom part missing.
Why would the PO not replace the oil thermostat?

For the head rebuild, I was considering doing this myself by installing all new valves, guides, springs, and seals. Can I just lap the new valves or do they need to be ground? Or is it better to have a shop do the rebuild ?

[JJ 911SC]

Originally Posted by roadster49

... Why would the PO not replace the oil thermostat?
...

Who knows why PO's do the stupidest things at time.

I heard a good one on Sunday; The PO of a Porsche buddy had screwed his amplifier on the gas tank. When buddy pick-up the car (the PO had removed the amp) he could smell a "gas leak"

In the thermostat case he might not even known that there were something wrong but the missing buttom is kind of strange... Could have been a twice remove PO.

It happened all the time with studs, the "surprise" valve adjustment...

Good Luck

[Flat6pac]

You havent had fun until you work on the studs broken below or at case level.
Bruce

[SCadaddle]

I'm in the same spot having just removed all the lower head studs in my 82SC and replacing them with steel studs. Since we used a propane torch to heat the case inside the spigot areas quite hot, my concern is have I ruined the rubber O rings under the acorn nuts on the case, and if so is it safe practice to say replace them one at a time---I'm still on the fence as to rebuild the bottom end of the engine with 156k on the clock....

[Baby]

I'm in the boat, too. With a broken head stud and a motor that had never been torn down, I opted to go all the way in. Just picked my stuff up at the machinists'. As for valves, for what it's worth, I had them ground. Also replaced three due to wear at the stems.

[lindy 911]

Judging from the amount of dirt visible in your photo, I would split the case and check out the bottom end. There is no good way to get your case clean when it's partially apart like you have it. Had you cleaned it well before disassembly it would be a different story. Your internals do not like dirt.

If you do decide to just put it back together, the through bolt o-rings are easy to do one at a time. Read up on the procedure and take your time. If they leak after it's back together there's no way to fix them without an upper end tear down.

Have a machine shop do your heads. At 130K they will need guides. Good chance there are some E valves worn beyond reuse. Guides are key here; get good ones from someone like Pelican or Supertec and move on.

I would replace at least ALL the lower studs, not just the broken ones, with steel studs of your choice. Do not use dilivar studs which are the OE pieces that are now broken in the case. I like Supertec but there are others.

Clean is the key function here and you can't spend too much time making sure every part is as clean as you can get it. I spent over 2 hours on each HALF of my case. Not hard to do, just elbow grease.

[TibetanT]

Originally Posted by Flat6pac

You havent had fun until you work on the studs broken below or at case level.
Bruce

++1 Bruce; Couldn't have said it better myself!

Now subscribed and looking forward to the rest of the build. Good luck.

[roadster49]

I split the case and it was pretty clean:


But the No 5 journal on the crank has a burned spot, and the rod bearing was also dark. I did not feel any deep grooves:


The connecting rod is within spec. But this journal must have been starved for oil.

I am thinking that it would be wise to have a professional finish the engine rebuild as I don't know how to insure that if I rebuild it that the problem would be solved.

Suggestions are welcome. Thanks,

[Flat6pac]

# 2 and 5 are the end of the oil system. You can put in a bigger pump, Turbo or C2 or you might try installing a new set of main bearings even though yours look great and also install the cam oil line restrictors, or just the restrictors. Part number is 901.105.361.01.
In my mind I would rather loose a cam than a crank and the restrictors will put more oil to the crank.
Bruce

[roadster49]

Thanks for the recommendations.

I have another question:
To keep the costs down I plan to rering my allusil pistons and reuse the cylinders which are a bit wider at the top but look in spec. I did not find any broken rings although the oil ring was dirty.

If this is a terrible idea what pistons and cylinders are recommended? stay with 3.0?

[roadster49]

Split case
The dark spots on the bearing is oil;;

[Flat6pac]

If you dont want to be back in the engine I would not rering KS cylinders. Some say they do but why take the chance of failure. I have reinstalled alucil with good results, its usually the heads that are the problem and once theyre done compression is good.
Bruce

[Flat6pac]

You have one of the late production 3.0 motors built on a 3.2 case.
Bruce

[roadster49]

Once again thank you for your insights.

When I did the leak down I was in the 60 percent range.

Did you know it was a 3.2 case because of the oil drain?

If I were to buy new Pistons and Cylinders could I use 3.2 with the stock CIS?

[Flat6pac]

I got caught on this one the other day.
3.2SS is JE pistons and 98mm bore cylinders, a couple grand and your cylinders but prefer 3.2 cylinders for sealing surface.
The 3.2 of 84 uses a longer stroke crank and rods, same bore as 3.0, 95mm
3.2 mahle pistons on your crank wont work, wrong pin size too.

Bruce

[roadster49]

Decided to reuse the alucil and started to clean them up. This is a 3.0 l with a late model case. Do I need to use the Cylinder Head Ring Gasket 95mm, each, 6 req, 911 (1978-83)? I did not find them when I took the heads off, unless they were stuck to the heads which I shipped to the machine shop.


ONe other question, I found these little spots on the side of the cylinder. Can these still be used or is there a risk?

Thanks

[Flat6pac]

There is head gaskets in your picture.
You might advertise in forsale that you need a set of Mahle 9.3 P&Cs
The casting number inside the piston for Mahle is 95L67. Full good set should be $500 to 600.
You might match the single piston and cylinder in Alucil. All you need for one is the deck height size in the triangle on the base of the cylinder. The number is delta 5 or delta 6.
Bruce

[roadster49]

Again, Thank you