I rebuilt my '83 CIS a couple years ago because I was doing an engine rebuild. Made sense to learn the system. Use the CIS for Dummies thread. And get the books. I knew nothing about working on cars at the time, and just dove in and learned. I also maintain a '79 CIS system on my brother's SC. Both systems took some basic adjustment to get them running at their peak, but it wasn't rocket science. You just have to follow the steps. They both drove to Rennsport and back to Iowa last year without a hitch. I had considered going to EFI, but every system has its pluses and minuses. I like the reliability of CIS. Like others have said, you get in, start the car, and go. I have two friends with MFI cars, a 71S and a 72T, and both are always complaining about the system for street driving. Early S cars are cool, and I've logged a bunch of miles on the '71S. But to me the big port SC's are the sweet spot of all the 911's, with the later SC's a close second.

I've owned Both.. an 86 Carrera and now i own a 82 sc. I like the sc better..It has better low end torque and it's more nimble and agile, more rewarding to drive.. Thumbs up for the SC's..

I've owned my US '79 SC for 33 years. For the first 31 of those years I had zero CIS issues - the biggest problem that came along were broken head studs, which I finally dealt with when I had an engine out bare metal re-paint 2 yrs ago, which prompted a top end rebuild which included installation of SSI's, upgraded chain tensioners, and cat delete. After getting the car back, it didn't run as smoothly as it had previously. I had poor cold start and stalling issues. Rather than return it to the shop, I became a member here, bought or downloaded numerous books etc of the CIS system, and decided after 31 yrs of ownership at that point that it was time to LEARN about the CIS system. I went through the car's vacuum system and concluded that the line to the WUR from the TTY was the wrong one, and swapped after testing. Through the use of pressure gauges I found that the WUR was out of spec and swapped for a calibrated one from Tony Donato. I also went to an engine rebuild class that Tony hosted a year ago. My car now once again runs beautifully, and I make it a point NOT to fiddle with it. Bottom line is that at age 61 I found new joy in my car having taken the plunge to get involved with it, without having been much of a wrench. And I am SO glad that I purchased this car a ways back. I can't comment vs. later years, but I have NO regrets.

Jason

Have a similar experience. Learning about the Kjet system from the experts here, both present and the past, rebuilt the CIS system myself after a botched job by the local. As I said before, Porsche is still supporting these ancient systems so there's value in them moving forward.

To the OP, have a read of this thread referenced above and see if that sort of hands on appeals to you. Fun stuff to many of us. But this is the 911 tech forum, so there's that selection bias working. So you have to make your own choice.

http://forums.pelicanparts.com/porsche-911-technical-forum/758788-cis-troubleshooting-dummies.html

Thank you all for the reponses and anecdotes. I think my fear of CIS was a little misguided.

I will keep a look out for my G body 911, and after this thread I will add SCs to the mix.

Which book do you think is the best?

FWIW, I've driven my SC right after driving a euro 3.2, right after dyno'ing both. The 3.2 had gobs more power and yet it felt rather dead-fish by comparison. The 3.2 would pull harder, but the throttle response lagged. I suspect that this was due to the more conservative fuel metering of the EFI. Although it could be a heavier flywheel on the G50. The contrast was very present.

Anyway, almost 20 years, and no CIS issues to speak of. 81SC. Solid car. Very mechanical.

Try a European SC. Something like a 1982 or '83.

Actually the 81-83 Euro has the better power and lends itself to minor mods better with the higher compression engine, but hard to find now...

Iv'e owned my 83 SC Euro CAB since 2012 and couldn't be happier. Dropped the top last night for a dinner drive on a great summer night.

http://forums.pelicanparts.com/uploa...1562038427.jpg
http://forums.pelicanparts.com/uploa...1562038456.jpg

Yeah, got a '82 (930/10) with cams and SSIs. Love it.

yes you should buy an SC. :cool: absolutely. :cool:

they are awesome. I had a 1969 T, and now a 81 SC, and the SC is 10x more fun.

The 915 is great. really lovely box.

CIS was great in the 80's :D:D
Now, not so much. Lot's of people running less than optimal without knowing (and wrecking engines without knowing), and parts are getting scarce and expensive.
81-83 USA SC are the worst of the lot with the whole lambda system which is a black box of trouble and nonsense and general crappiness.
78-79 SC would be better, much better. There you have only a small amount of parts to get right. Get a good FD and a good WUR and you are basically set for life.

Because of the price and ****tiness of 2nd hand parts over here, i gave up on CIS a couple of years ago and went EFI. I even chucked out my distributor. It's awesome and nothing to go wrong. There are literally 3 15$ sensors running the whole car.
Simply turn the key at -10°C and drive off in the snow. I'll let the next owner take care of the rust :D

good luck.

I was originally looking at SCs before I found my 87 3.2. The problem I always ran into is that I could never find a SC that was original. Most of them had mismatched parts from other cars on them, or had MacGyver as the mechanic and used wire ties and bubble gum to hold parts together.

nonetheless, I've always like the slightly wider wheel arches of the SC.

Yes

They went through a period of not having much value but still being expensive to maintain. I expect many 996s will see much the same treatment over the next decade before the clean ones start increasing in value.

911 CIS Primer - References

I have the book by James Weber, and it covers a lot. Also use the website above quite a bit.

Which EFI setup did you go with?

911 sc
 

I bought my sc about 5 years ago and have thoroughly enjoyed it. When I first got it, I was very concerned about having no knowledge about the cis system, so I bought all the books, read everything I could find in the forums and on the internet and began to work on my car's system as needed. At this point I definitely am not an expert but I do feel comfortable with my acquired knowledge and ability to work on my car. One thing I did that has helped a great deal when tuning and problem solving the cis system was to install a AEM wide band air fuel ratio gauge enabling me to see what is going on with the system under all conditions.
In summation, I thoroughly enjoy my car and would strongly recommend the purchase of an SC.
Dave

microsquirt with EDIS, with bitz fuel rails. original airbox.

if more people with CIS cars would put wideband on their exhausts they would not believe what they see :)

Reviving this thread because in my search for SCs I referenced this thread and wanted to ask why the 3.0 is not a great choice for hot rodding?

I've been looking at multiple threads where people have 3.0s with upgrading cams, SSIs, PMOs.

CIS doesn't lend itself to a tremendous number of modifications. Select cam lift/duration, 3.2 P/Cs, different exhaust and that's just about it. A stock 3.2 with Motronic ignition/injection system allows a different chip and myriad internal (read: expensive) modifications. The SC engine is pretty bullet-proof and you get what you see. I'm biased, I've owned my SC since new in '83, so I'm probably not the guy to talk to about this.

I’ll do my best to answer a complicated question without over-simplifying the answer.

Take a bone stock 3.2 Carrera with Motronic EFI. You can drop in a Steve Wong chip and maybe a different muffler and you’re off to the races (sorry, bad pun).

There is no comparatively inexpensive option for the CIS 3.0. I’m not saying a 3.0 isn’t a great motor — it absolutely is — it’s just that from a cost perspective there isn’t much low hanging fruit. Just switching to SSIs alone isn’t cheap (in comparison).

I think a lot depends on your situation too. If you were facing an engine rebuild, that’s the time to make a call if you want to switch to carbs, EFI, or whatever... because you can select all the components like pistons, cams, etc. that work together as a system.

Several years ago I started talking to local builder Franz Blam about EFI conversions. His first comment was the pistons used in CIS motors is not a good choice for EFI. I have since talked to many others and they all more or less say the same thing.

Sure, you could do “just” an EFI conversion and ignore the piston issue, but then you’d probably want to change the cams too. And then the exhaust. And gosh ITBs look cool. It’s a slippery slope that isn’t easily avoided. If you really start adding up costs, you’re probably within spitting distance of a 3.6 swap. (But then clean 3.6 motors aren’t as easy to find as they once were.)

On the other hand, if you developed an end state plan, stuck to it and could live with doing things in stages, you could step in to some mods over time. Step 1: change exhaust, Step 2: change to ITB/EFI, Step 3: different pistons/cams when rebuild is justified, etc...

There aren’t any right or wrong answers, just more expensive and less expensive ones.

There are so many cars on the road nowadays running much faster and with way more ease and comfort, that even if your vintage 911 runs 250kmh or faster, it hardly makes sense to spend aprox EUR 18.000,- for e.g. a 3.4 tuning based on a 3.2 Carrera to achieve that.

I like my 79 SC.
I refurbished the entire K-Jet including testet fuel injectors.
polished the air intakes
gave it new SSI with a DANSK sport

it runs spirited.

maybe one day I'll give it the Max&Moritz tuning to 200/210 hp...

It is a great choice. The biggest problem, besides money, is meeting smog requirements in most locations.

ksluna,

The 3.2 with Motronic is a much better package, than the 3.0 with CIS. The 3.0 is great for hot-rodding, because the crippled exhaust, the crippled cams and the limitations of the CIS almost demand it be hot rodded. My CIS was dependable and could get the SC to drive very nicely, but the CIS leaves too much on the table.

On the other hand, SCs are lighter and more nimble than the Carreras. So an SC with a 3.2 transplant, is a very attractive combo, in my mind. Depends upon your goals. Everyone who advocates their setup is right.

And around and around we go.

Michael S. Jackson
'78 SC w/EFI & SSIs