Rebuild continues...need some general info.

Ok, here goes...

I'm getting impatient on this rebuild so I'm really wanting to get started putting it back together. I think I'll feel much better after I start reassembling this thing.
I have a ton of specific questions that I just don't know about and I'm hoping some of you guys with more general rebuild knowledge can help.
The first order of business in the reassembly of the case, crank, and rods.
Before I do this I need to know a couple of things.
First, do I just take my new standard size main bearings and fit them to the case or is there some measurements that must be made?

My wrench told me that I need to send my rods out to have the big end machined back to stock. Another gent. wrote me and said that he used to do this work in a machine shop and that hardly, if ever, do they actually NEED to be machined and it just ends up increasing the cross load on the rod bolts because of the metal that is taken away in the machining process.

And I read in Bruce Andersons book about these measurements for the layshaft gear. Is this something that I can do?

When I remove the headstuds with a torch to heat the loctite, do you apply the heat to the base of the stud or gingerly to the case itself?

Assuming that I can get the case buttoned up without too much trouble then it is on to the:

Pistons, cylinders, and heads.

This is going to be a waiting game (cash) but I do have a question.
When I reinstall the valves and springs, how do you measure and determine the number of shims that are required under the spring? Will it be different now that I'm replacing the valves and springs?

Also, in reference to Bruce Andersons book there is a diagram which shows a measurement being taken to measure the cams "end play" or something, to the intermediate shaft. It's supposed to tell you if your timing chains are canted or not. I've never heard any of you say how or IF you did this and I was just wondering.

As for my injection system I've sort of changed my mind a bit.
I was going to completely dissassemble the CIS but now I think I'll stick to this:
Thourghly clean, inspect, and replace the
Warm-up Regulator,
Cold Start Valve,
Injectors. As well as clean and polish the runners and the throttle body and replace all of the vacum lines.
My question is, when replacing the WUR and Cold start valve, do they need to be adjustmented or do they just swap out?
Anything else I should consider concerning the CIS system? It ran fine before the rebuild (minus the WUR and Cold start) so I'm hoping I can get away without tearing it apart.

Ok, so what are your thoughts?

thanks,



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Leland Pate

___79 SC Targa

I aswell could benefit from some of that information as it appears I am in the same boat as Lealand both in the rebuild stage and the cash thing...

As for the head studs, I removed mine by heating the case (you want to expand the case) but it turned out the 90% of them just came out with the vice grips and no heat.

Adam Roseneck

Help me with the exhaust stud removal too. I have more than enought to grab onto but can't seem to loosend them up to pull the broken ones (i'm replacing the good ones too, cheap insurance)



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1978 911SC 3.0
roseneck@cyberbeach.net

Leland:

Regarding the head stud removal and the application of heat, I have not done this yet but I was at the Andial Racing shop earlier this week while on travel to Southern California, and I asked their parts manager the exact same question. He said a couple things. First, try to remove the studs without heat; you will generally be successful. I suspect a quality stud removal tool available from almost any decent parts store would do the trick for most of them. Secondly, if you do apply heat to the case, be careful and go slow. He said, if you get it too hot, the mag case will melt without any warning, kind of like watching a welding rod melt- one second you see rod, the next you got a puddle! Then you'd really have a problem. Third, when I asked him about the use of aftermarket studs like Raceware and Timecerts, he said, "We build a lot of big engines here, and won't don't mess with that stuff." They use the current Porsche recommended studs, without inserts unless needed. I know that is contrary to the opinion of Bruce Adams, but I found it interesting and credible. Big qualifier: I was talking to him about my 964 engine. Best of luck.

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Steve
'89 C4

Leland,
I think I might be able to help a little as I'm probably a week ahead of you at this point in my rebuild.

As for the rods. The bore diameter in the rods is in the spec book, I don't have it in front of me but I think you said you had a copy of the book. If the bores are round and within tolerance you should not bore them. Go with the standard beraing sizes and just install the new bearing halves. If they are out of round or too big then you need to take the whole set in and have them all machined to the next standard size "1" and then you must order bearings for that new size. The spec books lists three (I think) steps in the oversizing process and gives the bearing size and bore size. I did not have to bore mine at 220K they were still perfect.

The layshaft gear can be checked for axial movement alone in the case and backlash can be checked once the crank is in. You need a dial indicator to check this. (specs also in the book).

I can't help much on the studs other than like others have said be careful. I have seen a few posts from Warren on this subject and you might benefit from doing a search on stud removal.

As for the valves, it's a little tricky to get the hang of but after you do 12 of them little b#@$terds you get better at it. There are several things to check on the valves before you even put them in. A,B & C dimensions. I compared mine to the old valves and after some measuring and converting erors I found out I was ok. The thing that really changes the shims stack is how much material was taken off when the valve seats are cut. Fortunately, mine appeared to all be about .020 inches which is the standard shim size made by the P folks so I went to the dealer and got a pack. This may vary depending on who does your valve job - be careful. The tough part is putting the valves together with only the inner spring to get the measurement, make changes, double check them after the change and then reassemble them both inner and outer. Like I said, after you get the hang of it it's not so bad.

The cam gear measurement is tough, both Haynes and Bruce Andersons book do a pretty good job explaining how to take the measurement. Basically you are checking to make sure the gears on the layshaft are in line with the gears on the cams, not cocked. I did this upon disassembly and it checked out ok. I'll start back with the same shims and make minor adjustments as required. But I'm a long way from putting the cams back together so that will be a while yet. The new 98MM bore kit is on the way.(The 3.0 will be 3.2 soon).

As for the CSV and the WUR. I don't believe there are any adjustments, at least I haven't found any.

Kind of long winded but I hope it helps. Feel free to e-mail me if you have a sticky problem. I deliberated over this stuff for quite a while before I started back.
Good Luck...


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78 3.0L CIS 911SC

The WUR is adjustable. There is a small plug that the internal bi-metalic stip mounts to, that can be tapped in (less control pressure), or tapped out (more control pressure). There is a tech article around on how to make your WUR adjustable, by modifying that plug.



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Bill Krause
'79 911SC Euro

Bill, do I need to adjust a new unit or is it preset?


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Leland Pate

___79 SC Targa

A new unit or a rebuilt unit should be preset to the correct spec, so no adjustment would be required. If you clean your existing WUR, you might have to make a small adjustment. Take control pressure measurements before and after cleaning. I've also heard that some people like to tweek their WUR to account for small vacuum leaks in older engines, but you can do the same thing by tweaking your mixture.

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Bill Krause
'79 911SC Euro

About WUR & injectors:

If you change because of rough running or something like that, you should check and fine-adjust the CIS system after the exchange. It can run smoother than you ever expected...

Jens

About WUR & injectors:

If you change because of rough running or something like that, you should check and fine-adjust the CIS system after the exchange. It can run smoother than you ever expected...

Jens

Leland,

As we discussed with pistons and cylinders, you can measure things first, and see if they need machining or replacing or not. Liek the above post suggests, the 'beg end' bore in the rod shoudl be checked for roundness. If it is still the same shape and size as when it left the factory (very possible), then it's not broken, so don't fix it.

This is also my feeling with the WUR, cold start valve, etc. You report they were working fine. I think you might be wasting your money replacing stuff that works just fine.

This is just my opinion, Leland. Given with a spirit of respect, for sure. Here is my wish list:

SSI $1500 (with muffler)
R Torsion $400
F Torsion $250
7:31 R&P $1000 (?)
Shocks $700

If I had a lot more money than I do, there are hundreds of things I would buy before I spent money to replace my WUR, which is working fine. Again, my opinion.

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'83 SC

Thanks for the tips guys,

I admit, I still haven't grasped the concept of the big end of a con. rod becoming out of round...unless it wore straight through the bearing or something, how can it become un-round?
A bit of good news is that a freind of mine works over in the Hydro shop and they have boat loads of expensive, ultra-high precision, measuring tools like calipers and micrometers that he is very familiar with so I think with his assistance and a spec book I can get some good measurments. It's not that I am incompetant, rather the fact that if I did it by myself I'd be worried I was doing something wrong.

My WUR is bad, that's why I'm replacing it. I'm replacing the CSV because it was only $60 and I want to eliminate problems.

I also suspect an injector is leaking so I replaced them all for good measure.

Got an email back from Engine Rebuilders supply and they said that they send cylinders to a company called Langcourt to be replated. He said they do Formula 1 car blocks in the UK. or something too. Anyone ever heard of them?

So if I measure my crank journals and they are in spec. than I can just use my new "standard" size bearing set without any problem? That would be nice.
Any other tips would also be appreciated.
Thanks,

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Leland Pate

___79 SC Targa

[This message has been edited by Leland Pate (edited 03-08-2001).]

If your rod ends are in spec and so are your rod journals, then yes, just use new stock bearings. I understand your anxiety, Leland. If/when I rebuild my engine, I will be worse than you, most likely. The great care you are taking to ensure a quality rebuild, will achieve the desired results.

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'83 SC

Leland:
You ask about Langcourt....
I have had Nikasil m/c cylinders refinished by them and was totally satisfied. Engine builders also use a company called U.S. Chrome.

Just make absolutely sure Langcourt knows what the finished dimensions of your cylinders are supposed to be. You should be able to get this info for them from the Porsche Spec Book or workshop manual.


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Doug
'81 SC Coupe
Canada West Region PCA

[This message has been edited by Doug Zielke (edited 03-09-2001).]