78 SC rebuild guidance (warning long post)

[weare138]

Hello knowledgeable people of the pelican board,

My 1978 sc is very tired (300k miles tired) and I think it’s time for a rebuild. So I have some questions and I apologize in advanced for the length of my post and if some of my questions are already answered elsewhere on this forum (I did my best to search).

1. Since I am going to have the motor apart I figure I should try to eek a little more go out of it while I’m in there. The problem I have though is that I live in California and have to pass smog and run off of 91 octane (I can pump 100 octane just down the street but don’t want to be dependant on high test gas). I know that I can have my cams reground to the 964 profile but will this affect my emissions? The next big thing I was considering was increasing the displacement and CR (I doubt my cylinders are still reusable with 300k miles and having been overheated once). I honestly can’t afford a new set of mahles but what about the QSC cylinders with JE pistons that Supertec has been selling? Also what kind of compression ratio can I get away with on California gas (with the 964 cam profile). Is the CIS injection capable of dealing with a significant increase in displacement like a 3.4 or will I have to modify it a lot to get it to work. Anything else that that I forgot?
2. I will also need to find a good machine shop to do the necessary machine work, valve job, etc. I kind of want a machine shop that will not only do the work but kind of hold my hand a little. I’ve never done an engine rebuild before and a shop that will offer some guidance and not take me for a ride would be great. (I have read Wayne’s books but that’s about all I know.) I live in Thousand Oaks CA and would like to find a place reasonably close. I am however willing to drive pretty far if the shops that good (and hopefully reasonably priced).
3. Finally, I would love to pay a professional to do this job but I’m too poor. So I will be doing the rebuild myself. I have an extensive collection of hand tools, engine stand, Hoist, but I am totally lacking in and of the special tools necessary to complete the job (crows foot, engine stand yoke, etc.). So if any one in my area would be willing to let me rent the tools for a modest fee or a case of beer that would be greatly appreciated. If your worried about me disappearing with you expensive tools I have some expensive things I could hand over for collateral.


Well, thank you for taking the time to read my posting and feel free to ridicule me if the answers to some of my questions were right in front of my face.

[dtw]

Welcome to the board. It is great to hear about a 300,000 mile SC motor!

What are the issues that are bringing you to the "need a rebuild" conclusion. Also, have you pulled your valve covers to see if you have any broken head studs? If you've had some broken studs in place for a while, it may mean additional head work due to damaged head/cylinder mating surfaces.

With 300k on the clock, there could be many hard parts that need replacement - this could bring a homebrew rebuild budget to its knees pretty quickly. Consider additional head work as mentioned above, worn out intermediate shaft gear and sprockets, cam sprockets, cam lobes, etc. The thing is, once you've torn down your motor, the can of worms is open and your existing budget may get blown out of the water. This can create the urge to cut corners, which you may regret when all is sealed up and reinstalled.

Just some things to keep in mind. Once the engine is torn down and you've got a rough idea of what needs replacing, you can bounce upgrade ideas off the board if your budget still allows. If you've got a digital camera, we can help evaluate wear to an extent, but your best bet is to cart your parts to a seasoned professional builder or machine shop that knows 911 engines. There are plenty in California. Some, such as Henry Schmidt, are active contributors on this board.

[weare138]

I want to rebuild because it does so so on a compression test aroud 100psi, smokes, makes very little power (less than it should), pitted cams, and once it warms up it seems to have minimal oil presssure. No broken head studs though. I want to rebuild it before it has some kind of serious mechanical failure=infinite expense.

I want to open it up clean the parts and have some professionals tell me what to do next. Only after they evaluate the parts will I decide on what I want or can afford to upgrade.

I'm not really running on a shoestring budjet I just can't afford to pay someone $2500+ in labor to rebuild it. I have enough budget to replace some of the expensive bits if they're a little chewed up. I love the car and am not afraid to throw some money at it since I plan on keeping it for a while.

[YTNUKLR]

Welcome to Pelican. You are thinking right-on to get the motor done sooner (at 300k miles) than later.

I am over in La Canada, when I'm home from school. Feel free to email me anytime, I would not mind helping you inspect your parts and give what advice I can. I am going to be at school in Berkeley but I imagine we could arrange some time during the fall, thanksgiving or winter breaks.

I use Ollie's machine shop in Santa Ana; kind of far, but high-caliber work. They really *know* Porsches. I do like Engine Machine Service in L.A., traffic can be a drag though...take as much time as getting to Orange County! There are, of course, some shops that can do more rudimentary work like cleaning, crankshaft polishing, flywheel/valve cover resurfacing, etc., for reasonable money and close to home.

I have been trying to figure out how to do budget (but high-quality) rebuilds for a little while now. Let's see if I can't do something.

Cheers

[greg bradbury]

ditto what DTW said,

Count on 12x exhaust head studs.
Cams may be pitted, if they are the 964 grind should be OK with the stock engine. If pitted factor in new rockers and shafts. With 91 octane I would stay with stock pistons unless you want to go twin plug etc $$$
Check the pistons for ring groove wear with this high miles. The liners may be OK if youv'e done your oil changes, but factor in new Pistons and liners as well. The heads will probably need new valves and guides and maybe flycut as DTW said.
New bearings for the big ends and mains. rod bolts. polish the crank
gasket kit etc
new clutch while your at it, machine flywheel.
how about the gearbox does it change OK - more $$$

This rebuild business is a real test of your love for the car. Think worst case senario and you won't be far off.

A fresh motor will surprise you with its willingness to get up and go, so don't discard the stay near stock idea, regardless of what the modifiers say. Sometimes the mods can get out of hand and you don't get what you expect and then more $$$ and less fuel mileage to boot.

Good luck. do it yourself is acheiveable but factor in the car being off the road for a good while especially if you don't have all your parts and tools lined up ready to go. Mine took about 3 months.