Disassembly Done ... Time To Rebuild 3.0

[arbita1]

So I've elected to start a rebuild of my 83 SC 3.0 engine. History is as follows:

205,000 miles without being split. Records indicate some sort of top end work done back in the early 90's but I'm not exactly sure what it entailed. Car ran fine with some CIS issues. Used a bunch of oil but mostly from leaks. The engine was pretty dirty. Compression tested good across all cylinders. No leak down test. Power seemed a bit down compared to others cars.

The plan is to go through everything. Clean check and only replace what needs it. My best outcome would be to only have to replace typical wear and tear items. Maybe I'll think about a cam regrind but we'll see.

I didn't post all my disassembly photos. It's not as interesting as the rebuild stuff. And it was pretty uneventful. Just one head stud that gave me some problems. And I cracked a fin on a cylinder head when removing from the cam tower. I posted that on a separate thread.

Here is where I am to date. I'll use this thread to document and ask for help. Enjoy. I'm hoping I will.




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[al lkosmal]

Matt,
Good luck with the rebuild.

regards,
al

[911 Rod]

OMG
Did you disassemble your whole engine will working on the floor?

[arbita1]

Originally Posted by 911 Rod

OMG
Did you disassemble your whole engine will working on the floor?

LOL. What? No...there's an engine stand in the foreground! I'm just storing the parts there. The other bay of my garage is taking up my wood flooring material as I'm in the middle of renovating my house too.


My first question on this rebuild.

I know Wayne's book says that the crankshaft is one of the items that should be sent to a Porsche expert for work. But if I'm only polishing it, can't any competent shop do this work? The crankshaft is really heavy to ship out and I'd rather not if I don't have to.

[911 Rod]

I had my crank done at a reputable crank place that knows every crank made.
It wasn't cheap and everything checked out for the good.

[tharbert]

Likewise, I had mine checked, polished and balanced at a local race shop. If you have to have it ground -1, you'll want to send it to where the journals can be re-hardened. There's lots of discussion about that here somewhere...

[arbita1]

I only have a caliper set so I ordered a large micrometer so I can take some better dimensions of the crank. Overall I think the bearing surfaces look good. I don't see any scratching. I noticed these two spots on the flanges. Is this normal?




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[SoyRacer]

Totally normal.

Photocopy a zoomed in version of the crankshaft specs and hand it to the machinist polishing the crank. Any good crank shop can polish and verify specs.

[arbita1]

The crankshaft is at the machine shop getting micro polished.

In the interim I am going through the connecting rods. So far they seem to be measuring on the smaller side of the tolerances. I guess that is good. However I am concerned how they look. This is off cylinder 1.


And the bearings.


Obviously the bearings are shot. Are these rods ok?

[prschmn]

That rod looks fine from here-no signs of movement of the bearing. The rods are tough stuff.
Just put some good bolts back in ARP? and if you have sufficient crush you're probably good to go.
Wrist pin bushing tight too?

[Mark Henry]

On the rods it depends what you are doing. If it's going back as a stock street car then OE bolts and nuts are more than sufficient. Even NA hot street the OE nuts/bolts are OK. 3.0 are stout rods, one point where it beats the 3.2 engine.
If you plan to bump it up then I'd get bolts.
If going ARP I'd get the big ends resized, if the small ends has even a hair of slop (rock) I'd do all the rods.

That said I did my rods with ARP bolts, new bushings and had the small/big ends redone.

[Mark Henry]

Originally Posted by arbita1

The crankshaft is at the machine shop getting micro polished.

In the interim I am going through the connecting rods. So far they seem to be measuring on the smaller side of the tolerances. I guess that is good. However I am concerned how they look. This is off cylinder 1.


And the bearings.


Obviously the bearings are shot. Are these rods ok?

I would necessarily call the bearing as shot, I would measure them to see if they are still within tolerance.
Especially the mains and #8, going by how clean your journals are.
Bearings today are not the same quality as the were 15-20 years ago.
I would check the tolerance and if they are good I would reprocess them with a DFL coating and seriously consider putting them back in service.

[arbita1]

Originally Posted by prschmn

Wrist pin bushing tight too?

The measurements on the small end seem to be close to the tighter side of the spec. My measuring equipment isn't top of the line. I will test fit the wrist pins and see how they fit.

Originally Posted by Mark Henry

On the rods it depends what you are doing. If it's going back as a stock street car then OE bolts and nuts are more than sufficient. If going ARP I'd get the big ends resized, if the small ends has even a hair of slop (rock) I'd do all the rods.

This is going to be a stock rebuild for a street car that gets driven 3 - 5k per year max. So I was not planning on the added expense of ARP bolts.

Originally Posted by Mark Henry

I would necessarily call the bearing as shot, I would measure them to see if they are still within tolerance.
Especially the mains and #8, going by how clean your journals are.
Bearings today are not the same quality as the were 15-20 years ago.
I would check the tolerance and if they are good I would reprocess them with a DFL coating and seriously consider putting them back in service.

Ok. I will measure these bearings and see what I come up with. I'll try to post some additional pictures of some of the other bearings. Some of them look worse than the one I posted.

[Mark Henry]

Rod bearings are cheap and I don't think they were an issue, it's the main set and #8 I'd focus on.

[jdbunda]

Good luck with your rebuild! My 3.0 is going back together now. Definitely an interesting journey...

[arbita1]

Originally Posted by jdbunda

Good luck with your rebuild! My 3.0 is going back together now. Definitely an interesting journey...

Thanks. I've been watching yours. You're moving much faster than me.

[arbita1]

Finished measuring the rods. Big ends all seem well in spec. Small ends too. However when I test fit the wrist pin it slides in very easily. And it has a very slight movement. So I believe the next step is to have the machine shop replace the rod bushings. Is there anything special about this operation on Porsche rods? It seems like any good shop can do this.

On the rod bearings i had liked the idea of reusing the bearings and having them coated if they are all in spec. They all looked pretty much like the photo I posted above or better. Until I got to number six. See below.



I can feel this groove with a fingernail. Something must have gotten in there. So I am guessing reusing this set of bearings is out. Correct?

[Mark Henry]

You could, it's only one scratch, but like I said rod bearings are cheap, I'd just replace it.
Main bearings are the one's I be interested in scoping right out.

Here's some bearings I've processed with DFL, new and used, done it on a type 4 and 911 engines. So far I have had good luck, but then I haven't torn down an engine to know how they are wearing.

[Mark Henry]

A set I practiced with as I refined my DFL coating process. You can see it doesn't fix large scratches.

[arbita1]

Ok. New bearings for the rods then. Thanks.