Should I go CIS?

[RD911T]

I'm slowly going through my 71 coupe to get it road worthy. As I've documented in another thread, I'm an hour or 2 from finishing the suspension and brakes. I bought a 3.0L motor without an induction system for it a while back. This motor has good leak down numbers and should be ready to go. Due to moving my business and other stuff, funds are a little scarce right now. I keep looking at different options for induction as it's my single largest expense left. I do need an oil cooler and lines, but that's another story.

PMO's are about $4400. I could buy some Weber's in the $1500-2000 range, but knowledgeable people on the board say I'm asking for trouble if I don't rebuild them and that would turn them into $3500 pretty quick. EFI is very appealing, but unless I cobble something together myself, it's approaching $4-5K. I don't have any machining equipment or experience to do something like that, so I'd need a turn key system on the mechanical side. I can handle the programming with my skill set and the help of a friend that's a programming whiz.

I've been watching the for sale board and recently saw a complete (supposedly) CIS system off a running 82 3.0L. This is the same year as my motor. I know I could get it cheaper, like under $500. Is this a rabbit hole I'm headed down? I've read enough about CIS to know when it's in good condition and running right it starts easy and provides good economy. The motor should have plenty of power to push my coupe very quickly no matter what induction system I use. It's a totally stock motor with the top end redone about 30,000 miles ago by a reputable guy on this board. I have had my dizzy recurved already by Barry.

Looking for input for the collective. If CIS is a decent way to go, how do I make sure I'm getting everything I need when I purchase a system?

TIA!
Tom

[prebordao]

CIS is definitely a decent way to go, but it has to be running ok and/or you need someone knowledgeable to assist you. Otherwise, you might end up buying a lot of needless parts.

However, with everything ok, I would say it's the system that gives you more bang for the buck. Absolutely plug and play.

[stlrj]

Originally Posted by RD911T

Looking for input for the collective. If CIS is a decent way to go, how do I make sure I'm getting everything I need when I purchase a system?

If you do a search on CIS, you will find lots of pictures of complete CIS injection systems for 82. Get familiar with them.


Cheers,

Joe

[Jack Stands]

The CIS may be the easiest as that's what the pistons and cams in your engine were designed for. You can always use that as a base to go with the Bitz EFI conversion in the future if desired. The mild cams that are standard with the SC engine limit how much bang you can get by switching to other induction systems at this time.

[MongooseGA]

I'll make you a deal.

You buy me a Bitz EFI kit, and I'll send you my CIS parts

[Damon in STL]

I'm getting ready to install the Bitz EFI kit on my '75 S with a '80 3.0 (received it last week). I have a spare CIS system I'm using as the donor for the EFI project and the car currently has a refreshed CIS system in it. I'm thinking about putting the one in the car up for sale once the EFI is up and running. I was going to take some video of it running prior to uninstalling for potential buyers.

The plan is to next move to EDIS ignition.....and maybe a turbo!

I'm in St. Louis if you are interested.

Damon

[RD911T]

Originally Posted by Damon in STL

I'm getting ready to install the Bitz EFI kit on my '75 S with a '80 3.0 (received it last week). I have a spare CIS system I'm using as the donor for the EFI project and the car currently has a refreshed CIS system in it. I'm thinking about putting the one in the car up for sale once the EFI is up and running. I was going to take some video of it running prior to uninstalling for potential buyers.

The plan is to next move to EDIS ignition.....and maybe a turbo!

I'm in St. Louis if you are interested.

Damon

Damon,

That's a great offer. I need to follow up on the 82 system first as that's the same year as my engine. Very cool e30 build. You are insane! I get up to StL every once in a while. I'll PM you my phone number, maybe I can stop by and look at your laboratory sometime!

Tom

[island911]

CIS is pretty tough. There certainly are more 3.0's running CIS than anything else.

And, with a few people experimenting with aftermarket EFI systems, you can get the CIS on the cheap (relatively speaking).

The only potential gotcha I see is that 3.0 motor you have. If it has stock(ish) cams, you should be great. But if it was built for carbs, the CIS might not like the mid-range.

[timmy2]

CIS in great condition with all components in working order is a great system. Once things start to fail, the NLA parts cost to rebuild and replace easily starts to approach the cost of the Bitz kit. $450 or more for the air box, a few more hundred for each of the WUR, AAR, and others, many more hundreds for the FD. New injectors, seals and sleeves etc add up fast.
Gauge set, CO tester. Etc, etc, you get the idea.

For your '82 engine you will need to make sure all the O2 Jetronic controls and wiring come with the CIS. (Lambda)

[Dodge Man]

I do not drive every day and my CIS (or an EFI) tolerates short term storage a lot better than carbs. Carbs are great for performance but carbs do not usually dial in right out of the box and tuning $$$ are required. A working CIS matched to your engine year and country will probably be the easiest & least expensive way to go. IMHO Try to get a CIS that was used on your motor year model/country years because the technical manuals will be spot on for tuning. However, you will have to search the threads for how to connect the fuel lines or adapt/change/replace your fuel tank for CIS. Do not forget the fuel pump change too. I like having a 20 gallon CIS tank on road trips. Make yourself happy and please put the old 71 motor on the shelf with ATF in the cylinders (old school, turn it over every few months too).

A stock US 3.0 probably will not be too hard on the 901 trans but if it is a numbers car that you want to resale one day, then you may want to consider a 915 upgrade to save the numbers parts for future resale value. Especially if you want to track the car. IME Gears/parts for older trans are VERY EXPENSIVE. Have fun & good luck.

[RSBob]

I have 2 3.0 motors. One with stock CIS and the other with new Webbers. The one with the carbs took a while to learn exactly what it wanted to start without stalling. The CIS fire right up each time. The carbs are huge gas wasters, while CIS returns decent fuel mileage. After driving the carbbed car and parking it in the garage, it reeks of gas as it evaporates out of the stacks. I put an exhaust fan through the wall next to the car since the smell was getting into the house. The CIS has very little smell. The carbs put out much more obnoxious exhaust smell which always isn't fun on hot days with the windows open. Carbs are retro and sexy, but CIS is just so much nicer when it runs well. Oh and performance-wise, I don't feel much difference.

[zelrik911]

When you are familiarising yourself with the 911 CIS, dont overlook that the CIS system circulates a lot more fuel than is actually used, so you must have an adequate return fuel line into the tank.
The CIS fuel tank also has an inbuilt baffle system called a surge pot. You could probably run CIS without a surge pot, but you would absolutely need a return to tank fuel line.

[tirwin]

At the end of the day, CIS was an intermediate technology between carbs and EFI. I don't think there is an easy answer. If you can match the same year CIS to your engine and you can get a working system, that is probably the cheapest way to go. Every choice has it's warts. I have thought a lot about following the lead of others and going the Bitz route. But that is a slippery slope too. I even thought about putting a 3.6 in.

What will the availability of CIS stuff be in another 10 years? Hard to answer that.

[BoxsterGT]

Good advice from Jack S.

A very practical way to go. If you have a "complete & running" 82 CIS system the install is pretty straightforward. Lots of help from this board if you have questions.

If you ever want to change to EFI you have all the basics still there on the motor.

Here are photos from when we did this conversion work quite a few years back.....



This one shows the EDIS mounted on a simple Aluminum angle bracket.......



On this last one we wanted to keep it as original appearing as possible. A California SC Targa in spectacular condition.......



In every case the conversion turned out to be worth the effort. And with the closed loop system the fuel mileage improved as well.

Len at Autosportengineering dot com