Inherited '80 911 SC Targa-- Can someone please explain this CIS/Carb stuff to me?
 

Hey Gents-

Glad to have found a resource for this stuff and I'm hoping you all can help me out.

I recently inherited a 1980 911 SC Targa from my father. It has 55xxx original miles. It needs some work, including a good detail, but otherwise is in good shape.

I've begun sourcing tune-up standard parts for it, as its been sitting in our garage untouched for 10-15 years. I've ordered new filters (air, oil, fuel), plugs, coil wires, distributor, front/rear hood shocks, etc.

It hasn't been running, so I have to purge the system of the old fuel, etc. before I really get to messing around with it and try to get it running.

I've spoken to two Porsche independent mechanics now who have mentioned that its going to need serious engine work with something to do with the fuel system. They haven't even looked at the car and they still say that.

They both suggested that the work is going to be pricey and mentioned switching to carbs and going away from the fuel injection.

Can someone please explain to me what the heck they are talking about and why I would need to throw that much money at this thing already? I did some searching and reading and found a few discussions about carbs vs. CIS but honestly, its all gibberish to me even though I know a bit about engines, etc.

Thanks

Welcome, apparently your post got overlooked. Usually members jump on new posts pretty quick. First thing. It's not real till we see some pictures :) Second, lots of info on CIS. It's not a complicated system if you take the time to read up on it some. You'll need a set of test gauges for sure. Most issues with CIS are either vacuum leak(un-regulated air), mixture issues when a someone has attempted to compensate for a vacuum leak using the mixture adjustment or warmup regulator issues. I wouldn't scap the CIS personally. I have an 83 RoW and with a little effort and some good advise from Pelican members mine is working as it should regardless of ambient temperature. Post those pictures and welcome to the group. Warren

Search for CIS for dummies thread. It will enlighten you. :)
Now post a picture of your car!

YA, what he said!

Drain the fuel out, put fresh fuel in with a heavy dose of Techron. Drain the oil and put a fresh filter on, I wouldn't worry about what oil as I would run it 100 miles and drain it hot and THEN put in something good. Put in a fresh battery and see if the gauges light up and the CDI box (finned aluminum box left side of engine compartment) whines with the key on. Pull the coil wire off the coil, remove the fuel pump relay in the front fuse panel, and have someone watching the engine and under the car for fuel leaks... then turn the key. Let her turn over until you see the oil pressure gauge go up. Put fuel pump relay back in, connect coil wire, and see if she kicks. If not, diagnosis time begins! If by some chance it runs well enough to drive, don't. Pull the four rubber brake lines off and replace with new, then flush/bleed the brakes with ATE Gold (street use).. Good luck and welcome!

If you go swapping out wire, cap, etc. etc. before knowing what you have you can possibly mess something up, I would only change out one thing at a time, after it's running... if it runs of course!

I have an 82 SC going through a carb conversion. It's a lot less plug and play then it sounds... The cost of the carbs is just scratching the surface.

I have a huge list of parts, part numbers and vendors on a pivot table/spread sheet I can send (pm if interested). It might be helpful to see the kinds of work I have done outside of the carb stuff.

Start with a plan.
CIS and Carbs involve a lot of debugging to isolate problem areas. But go through the steps one-by-one, verify and test one component at a time. If you start swapping parts you will never chase down the issue. CIS for dummies, as timmy2 suggested, is the place to start, there are quite a few experts on both CIS and Carbs here, so after you run into a wall they can guide you around the sharp corners. Grab a few 911 books as well including 101 projects by our host, and download the PET parts manual (free) from here too (get familiar with where things are located and where they are connected).

The good news is there are lots of resources, but you have to do your homework first, and explain what you did, and where you got stuck. Also, identify where you are located and there might be a few pelicans where you live, willing to give a helping hand.

BTW: I have carbs so I am in the other camp, but I would not recommend one over the other until you know what you first have!

Good luck, and keep us informed....

Welcome aboard.

Despite what your mechanics are saying, I wouldn't dump the CIS system. I personally have been working my way through the CIS system on the 79 I've been working on - addressing various issues (most of them vacuum related) to get this thing working correctly - and I still say that the CIS is relatively simple when you get right down to it's core.

Starting simple, I would (as suggested by GaryR) drain the fuel, put in 5gal of fresh and look for fuel leaks, then give it a shot.

Let's see some pics!

CIS is a "hydraulic" signal based fuel injection system that was designed not for power but for fuel economy and emissions. It was superseded by modern electronic fuel injection systems.

People often put carbs on CIS motors to gain improved power, sound, and throttle response. I hear from usually reliable sources that CIS is very sensitive to corrosion caused by Et-OH fuels prevalent today. I take pride in having deCISisified 2 911s.

CIS beats carbs in cold start, economy, and emissions - none of them sports car design features.

Just tacking carbs on a CIS motor does not realize the full potential as the cams for CIS suck. But you cannot just change the cams, as the piston shapes will not work with good cams, so it gets expensive.

But it is worth it.

You can stick the carbs on, and do the cams & pistons later. Speed costs money - how fast do you want to go each year?

Of course you can always convert the CIS to EFI like I did.... :)

Welcome! If the car has been sitting for this long, there is chances that you will have some issues with some of the components of the CIS, the same would be true for any types of system. I would carry on what you are doing, you are on the right track (flushing old fuel and oil, replacing spark plugs, distributor cap and rotor and all filters). You will only know "if" there are any issues once you start it.

I would do a visual inspection of the fuel lines once you have new fuel in the system. Pressurize the system before putting a spark and look and smell for any hoses that are leaking. Once you are confident you have no leaks build the oil pressure and then start her up!

Once you have it running create a baseline of your fuel pressures. Once you have those you can truly get to troubleshooting.

Carbs or CIS: it can become a slippery slope no matter what you decide;)

You can only switch to EFI like you did once you have your Level II CIS badge. :D

Hello David, welcome to the club. I am in a very similar situation as you since my '79SC was also stored for 16 years without moving. As yours it had only 50,000 miles on it. Actually I bought it brand new in 1979. I wanted to put it back on the road 23 years ago and thought it would be easy because it ran great when it put it into the garage. I had it flat bedded to a shop to do all the regular stuff: Oil change, transmission oil change, new engine compartment fuel filter, new oil filter, slowly rotating the engine first, running it without sparks first, etc., etc. The hang-up turned out to be the caked-up gasoline at the tank bottom and inside the fuel pump. The pump was frozen and the tank inlet and outlets were plugged up. The tank mesh fuel filter was clogged up with syrupy to sold brown solid fuel residue. After thoroughly cleaning tank inlet and outlets, replacing tank fuel mesh filter, replacing the fuel pump. the car started it's new life again. And it has been running flawlessly ever since. The only issue I have now is occasionally hesitant starting procedures.

I would get it running first and then see what you want to do with it or how you want to modify it.

CARBS would be going backwards.

get it running and fix/tun up the CIS as has been suggested.

Congrats, welcome SmileWavy! CIS is fine, like anything else if maintained, like others say. Please don't feel forced to have to replace it (for NO reason). I've never had any issues & I drive it a lot (incl. cold temps. like -15 Cel. in Canada). Besides for me CIS has been absolutely reliable without so much as even an adjustment for 6 years on current 82' SC, although I maintain filters, use high grade fuel (min. to no ethanol), inspect for leaks & if found always address ASAP, keep engine & eng. bay very clean etc. This is not an exception, I've had other CIS P cars with no issues, albeit some slight seasonal 2 min. lean/rich adjustments, that's it! ;)

Lol, working on my EFI badge now so I can go to TBI... :)

To the OP, (David)
Search and Follow the commonly neglected maintenance thread as well as many other long term storage start up stories and read, read, read. An advanced title search is your best friend here.
Then teach yourself how to do the work as it is fairly simple once you have the knowledge base and tools.
The tools price is more than offset by the savings in shop rates....
Keep us posted and post a picture of your car already... Sheesh...! :)

Welcome David

If your dad's car had an OK CIS system when he stopped using it, there is a high probability it will be good enough for you to get the car running so you can sort through any issues and make INFORMED decisions on where to go next.

This is based on my experience of getting many other european cars with CIS started up after many years of sleeping.

I have found that the fuel tank is the main culprit. You are correct to replace all the old fuel - BUT also check that the outlet to the motor and the RETURN to the tank are completely unblocked. A blocked return can cause many issues that get mistakenly blamed on CIS. Tank sludge will block the internal filters & swirl pot.

Carbys for 911's are very expensive these days - perhaps $2K for a good set? That cost makes CIS components look cheap by comparison.

Good luck
Peter

PS: see PORWOLFs comments above which I have found in many 'sleeping beauty' CIS cars.

It depends.........
 

Hi David and Welcome,

My father passed his beloved 74 coupe to me. He was an engineer, retired, a great furniture worker, but did no mechanical work himself, which brings me to a very important initial question, - do you have the maintenance records?

If he was up on the wheel bearing pack, trans fluid change, cv packing, fuel hose replacement and perhaps most critically, oil changes and brake fluid changes prior to storage, you stand a much better chance of not suffering water/rust related damage, than if the car was just "rode hard and put away wet".

Do you want to do any of the work? Have space? time? and tools???

Or,Do you have a good mechanic?

Any Rust???

Are you going to keep the car, "No matter what"?


It might be good to do an initial assessment. I think what the 2 mechanics were referring to was the overhaul of the fuel system, which may be all gunked up AND need all of the fuel supply, return and evaporative lines replaced - this can get expensive, particularly, if you aren't doing the work yourself. If you are well healed and this is a family car you want to hold on to then all is well.

I think some of the prior recommendations to study threads covering the rehabilitation of cars long asleep will be a productive study.

After 10-15 years in hibernation, no matter what, you are going to be looking at a lot of repairs, like suspension bushings. Rust or interior rot could be a total killer, (was it kept dry).

After my fathers passing, I took it to Snyders in santa Barbara, the firm that took care of the car for my dad, asked them to check the timing and mixture, because the car ran hot, (AC and no front cooler), before I drove it 500 miles to my home.

When I got it home, (very sentimental/memorable drive, no problems), it was leaking fuel from an original return hose, got that fixed then proceeded to install an 85 front cooler, original thermostat and brass oil lines to the front right fender and a couple of new axle assemblies, factory short shift kit, replaced a rocker panel and painted it to match.

Shortly there after, the block thermostat popped up, out of the block, (pulled magnesium block threads) and I lost 12 quarts of oil in about 3 seconds, flatbeded the car to the shop and proceeded to pull the engine/trans, strip to the long block and refresh everything on the way back out.

Next put Wevo rear antiroll bar mounts in, replaced the missing 18 mm carerra bar and moved the fuel pump to the front, under the rack.

After replacing 20 year old Pirellis with Dunlop direzzionales, I was into the car about 12k, but I am really ok about this because it was dad's, now my car.

I am now restoring the front suspension, ER bushings Por-15 paint, new discs, PMB calipers, ss brake lines front disc cooling system, rack overhaul, new MC, bilsteins, bearings....

Dad really loved the car, kept it up, had it repainted sepia, (stock color), did a bit of upholstery work, refinished the 6 inch Fuchs.

Cars were a strong bond, I really miss him. I will do the car right, (but my way :-)
chris

So, I think it is very easy to go down the "slippery slope"> Do a thorough assessment of the car's needs, so you don't end up unhappy with your dad's car







http://forums.pelicanparts.com/uploa...1395805187.jpg
http://forums.pelicanparts.com/uploa...1395805384.jpg

A marvelous car - welcome to the BBS.

Don't worry too much about the car. A bit of fresh fuel and oil and if you Dad can see you he will be proud. Your Dad was a smart man getting a SC.

Enjoy. And buy the books (Wayne's 101 book and the Bently book), you will be surprised how easy these things are to work on.

Thanks to all of you for the kind replies and advice! First off, no worries about the delayed responses. Apparently, my post required moderator approval since I was so new, which makes perfect sense. I'm glad that it eventually made it through that process and you all were able to see it.

Let me also clarify that I'm not really LOOKING to modify the car. Quite frankly, I would love to keep it just the way it is. So I'm not anxious to convert to carbs or to have to install a whole new injection and management system. I only brought that up because a mechanic I spoke to recently and one i spoke to a few years ago (the last time we considered working with it) suggested that the fuel system probably wouldn't work, parts would be impossible to get, and a conversion was inevitable.

As I say, I'd like to keep it stock for the most part, to preserve the original spirit of the car. It's never going to be a rocket ship.

wolds (warren) and timmy2: thanks for the welcome. I'll be sure to look into that thread and I'm sure I'll find the information beneficial. And EFI does sound interesting...

GaryR: It's as though you read my mind. That was basically the exact procedure I was going to use, though you put it in words (I had it in my head haha).

Ayles: Thanks for the offer. i'll PM you if I need the list!

Jfporco: Thanks for the advice, sir. I have indeed ordered the 101 projects book, as well as a Bentley manual. I can't wait to have them in my hands and read up on a few of these systems.

Robey5: I hope I can stick with what I've got. Thanks for the advice and welcome!

RWebb: Very interesting information here. Definitely clears up a few things for me. A part of me would like to see better performance out of the car. But lets be honest here, right? Maximum output realistically from this engine, with carbs, etc. for a street application (naturally aspirated) would be like 240hp. correct? I guess since the car only weighs 2700 or so pounds, the performance numbers would be ok, but not exactly out of this world by today's standards. 0-60 in the upper 5s, low 6s maybe? I mean, modern camrys are faster than that. I'm just no so sure that going all out on the engine for performance is going to be worth it. Maybe I'm wrong? Thanks for the information and welcome!

Festive_Zombie: Thanks for the advice! I'll definitely come back to you guys about the fuel lines, etc. I need to run down the procedures to check the pressure, etc.

porwolf: God, it does sound like we were in the exact same position! I was going to have this one flat- bedded out of here actually, but I figured that I could do quite a few of these jobs myself in my garage and save some money. if I can't get it going, I'll have to go with the flatbed. Thanks for the information and welcome! I may have to PM you at some point to compare notes on a few things.

zelrik911: Thanks for the welcome and advice! I'll keep everyone informed on my progress.

To the rest of you I didn't address by name, thanks very much for your welcome words!



Now, i do have a first/followup question for you all!

I pulled the fuel filter from the car and it was a Purolator PFC-6. It was so old that it actually says "West Germany" on it. I did some searching around here and through google and couldn't find any definitive alternative. I called porsche, which offered to sell me an OEM unit for like $80...told them to pound sand. I visited a few auto parts shops near me and even called Purolator directly; none of them could really help me.

I ended up going to a local shop here and he sold me a Mahle K40 filter, which he said was the correct filter for the car. He is a porsche guy, so I bought it. Is this correct? It seems ok...its roughly the same size of the Purolator (a little smaller) and the fittings fit when I swapped them over. I haven't tightened them down yet, and I'm using a crush washer (which I think is correct). Can anyone confirm?




And as requested (and you all earned them with your welcomes and replies), here are two pics. Sorry they aren't great...taken with my camera phone. I waxed it today...2 coats minimum on the body to restore the paint. It's still not done, so go easy on me ;) Interior is next while I wait for parts (so no pics of that yet).

http://farm8.staticflickr.com/7388/1...489a8146_b.jpg

http://farm4.staticflickr.com/3784/1...95ded887_b.jpg

i got a stored 75 car started. if i can, so can you.

was it easy? no! was it kinda expensive? yes!! but to be honest, both situations would have been better if i cracked opened a book or two. there is a great CIS book out there..there are two actually. one is easier to understand, and there are pictures!! get that one. i have it in my garage if you want a pic of the cover.

AND..i think it would help if you posted up your location. you would be surprised who would show up to help..all for a beer and a slice of pizza.

pull the tank sender and take a peek..if there is little to no rust..you would be leaps ahead of the hot mess i inherited. and find CIS gauges. dont buy expensive ones..i did, and they look EXACTLY like inexpensive ones.

CIS for Dummies
 

CIS for Dummies is a good place to start.

I knew absolutely nothing about CIS and got my 1980sc all sorted out with the help of this Forum. (also purchase Wayne's Book & the Bentley Book)

You can do it and it does not have to cost a lot of money.
My car has 300,000 miles on it and it now runs perfectly after I followed the sage advice of the Pelicans who were very generous with they time and knowledge.

You are in good hands and you have a great car.

I'm surprised that no one has mentioned the CIS Primer site (aka Jim's Garage). it really has a wealth of info and the specifications that you need to have a properly running CIS car.
911 CIS Primer - Index

There is a good chance that you will ultimately learn the hard was as most of us have been this route. I personally spent 2 years making my CIS progressively worse by tweaking things. Only to discover that once I had my fuel pressures set correctly, everything else started working.

CIS is really a very simple system but takes a while to grasp. it's basis of operation starts with proper fuel pressures. The correct fuel pressures will control how the fuel piston moves by using fuel pressure to dampen a small piston. Too much fuel pressure and the piston is hard to move and too little fuel pressure and the piston moves too freely. In either case, it's impossible to regulate the air/fuel ratio. Fuel pressures also vary depending on engine temp so there is a device that controls this (WUR).

You will have to read up on how all these things work together but the most important concept with CIS is to realize there is an order of operations. Certain things must be set first before adjusting the next and the key is to get the correct fuel pressure first. This is done with a relatively inexpensive tester that measures the fuel pressures at different operating situations. 1) system pressure = fuel pump main pressure. It is set to a constant rate of around 5 bar by a regulator spring within the fuel distributor and shims. 2) cold pressure = cold control pressure = fuel pressure out of the WUR before the WUR has heated up and 3) warm control pressure = fuel pressure out of the WUR after it has heated up.

The cold and warm pressures affect how much fuel pressure is applied against a piston in the fuel distributor. You might think of this as a nozzle on the end of a hose. The WUR uses springs and a metal disk to make it either easy or difficult for fuel to flow against the piston. Once those two pressures are set correctly, you fine tune the mixture and the engine will run fine for a very long time. Later versions, such as your '80 SC have added components that affect air flow. Most of these added devices are for cold starting assistance and once the engine is well warmed up, most of these devices don't do anything.

Bosch makes a very simple book on understanding CIS that explains the system well and the CIS Primer site is another great source of info. Lastly, I learned a whole lot from this board as there are some true experts here (I'm not one yet but getting there).

The following old-school, K-Jetronic/CIS video is also worth a look-see.

Bosch K-Jetronic (CIS) explained - YouTube

Phew Ronnie. I'm pleased there wasn't an exam at the end of that youtube.

Excellent video, makes me feel smarter with that British accented narrator. If you understand this video you understand how CIS works. It's a simple system and works well if properly maintained and correctly set up. Warren

Thanks Ronnie for the video, many this really helps :)

When you drain your fuel, replace the filter/screen inside of the tank. This keeps the truly big stuff from going into your pump, but it tends to plug up with time (and especially after sitting). I consider it an "odd ball maintenance item" every 20 or so years on these cars.

Had a friend who fired up one that had sat for a few years. He went through three fuel pumps, which are rather expensive, before I convinced him to replace that part (host sells the part). Car ran like a clock thereafter.

This is the part # from our host: 911-201-141-00-M100

Just one more item to add to your pre-startup list.

angela

The replies to this thread have been fantastic. Thank you all!

The youtube video really helped me understand the system. It's simple on its face, but complicated in its nuances from what it seems. I totally understand the importance of the fuel pressure after watching the video. And I can also see why they abandoned this ultimately and went to EFI...there are just too many moving parts/failure points from my point of view. I mean, if for instance, one of the springs in the valves goes out of spec, it could affect every component down the line.

I'll read up on the system some more on Jim's site to make sure I understand it.

Apologies again for the delayed responses. I'm posting this at 2:04 eastern time, but I'm guessing this one too will require moderator approval, which slows down the true post time.

Anyone have that information on the K40 filter from my last post? (Bottom of page 1).

TidyBuoy, great summary explanation. Thanks.

David,

Congrats on getting the car.

In reference to the CSI vs. carb discussion, my suggestion would be if the car has not been messed with and the K-Jetronic with Lambda CIS system is complete, then stay with it. When it is fully functional it works as designed and granted you will need to learn how the system functions under the different operating conditions. I agree with all of the previous recommendations on reading material and also I would recommend the Bosch Fuel injection manual. It has a lot of technical info on the design that I found to be very helpful in understanding the system.

Pat

+1 on Jims CIS primer.

I just thought I'd add an addition to the thread about service records. I have some, but my father has never been (nor ever was) a great collector of them. So I've only got a few of them, but I do have the original Owner's Manual and Warranty and Maintenance Manual. Unfortunately, I do not have the original window sticker or receipt of purchase (other than a sheet which certified the mileage at the time of transfer).

Too bad you are too far north or I'd stop over and give you a hand.

Haha thanks for the offer man! I've got quite a bit to do with her before I attempt a start so I'm not too convinced I'll need outside help...yet SmileWavy

YA, what he said!
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Going through the car tonight guys...my parts came in.

I need to know what a good oil to fill her up with is. I'm in Florida, so it's hot and humid. Thoughts?

any oil that is 20W-40, you will run it 100 miles then drain it and repeat for 500 miles

after that, switch to Brad Penn

Cool, thanks for the input.

Next question. The plugs I've been pulling out of the engine are old Bosch W6s.

The ones I ordered from our sponsor are Bosch WR-5-DC+S. Are these compatible? They say they are when ordering, but it admit that I didn't look at the ones that came out of the engine until I had replaced 3 of them.

Nice car.

Do not let the CIS naysayers poison your thoughts. If what you want is a nice car to drive every day, CIS is hard to beat. If you want the last 1/10% if it's performance, Then by all means go to carbs or EFI. For what you will spend to convert , you will have paid several times for the CIS rehabilitation. You will find CIS easy to start (carbs can be finicky on a 911), good mileage and very robust. I have had my 1973.5 (world first production car with CIS) for over 10 years and it had not needed anything other than a minor adjustment 9 years ago.

Keep what you got and educate yourself or find a mechanic who knows how to
maintain a CIS system.