Weber 40 IDA on a stock 3.0

[ssrodder]

Completely disgusted with the CIS on my '82 911SC. Car had sat for over 4 years before I purchased it. 59,000 miles. Have changed just about everything from the tank back. Been working on it for over 2 months. Starts then immediately stalls. Had it running in the garage one day after I worked on the WUR. Now it's back to start then stall. A friend has a set of 40IDA webers that he will sell to me. Took them off a 2.7 911 about two years ago when he changed to a 3.4 and went EFI.
My '82SC will just be a warm weather toy. No racing.
What changes will I need to make my '82SC driveable in normal traffic with the Webers. I'm not interested in going EFI. Appreciate all info both positive and negative.

[petrolblue83911]

I've had both stock cis and webber'd SC's,

if I was in your postion the first thing I would do now would be to bite the bullet, and find a good 911 shop. get the car diagnosed, and find out what is wrong with it. If you have already gone part fishing, then you know, to some extent what isn't wrong, but seriously, for a good shop, it should not be hard to figure this out.

well running CIS is far superior to Carbs on a stock sc motor in terms of reliability, MPG, and driveability. Now, if you are looking to back-date the exhaust, put in a mild cam...etc.. then, carbs can be a ton of fun.

[ssrodder]

That's exactly what I need to know. When I purchased this '82 it came with a single inlet dual outlet muffler, which I know is not stock. It also looks like the motor was worked on at one time before it was parked to seal up some oil leaks on the bottom end. It has expandable oil tubes installed. Right now the only leak it has is on the s tube from the oil tank which I will replace after I get it running. I changed the oil before I started this project, and will changed the oil again after I get it heated up. What cams would you suggest and what other modifications. I do not want to change the pistons.

[brads911sc]

Whats the downside to Bitz Racing EFI on the SC? That is what is was designed and made for... I have not made the plunge... I have a good shop that has my CIS working fine for now. If I had issues, Id switch to the Bitz system. Cant find anyone who doesnt like it...

[petrolblue83911]

srodder,

well, good questions on cams, the thing is, I would start with making sure you know what you have right now. if you are confident that all the internals are stock, and you dont have any need to pull the engine right now, I would focus on determining exactly what is wrong, and then go from there. I do most of my own work, but if I get stumped, its no shame to have a pro look it over.

if you are convinced that you want to go with carbs, do a search on 911 sc carbs, and start reading, also search 911 sc and PMO carbs, all the info is there, and you'll find the names of the posters who really know all the options out there.

[Otto]

Set the CO with a CO machine. I can't belive anybody thinks carbs are better than CIS.

[RoninLB]

CIS is a great reliable street system. A new 911 owner will learn plenty about the car with stock and still have fun doing it.

[Jared at Pelican Parts]

Without making internal engine changes, carbs are kind of a poor choice. CIS is not that hard to figure out, really. I would invest the time and money to getting the CIS sorted out. What have you done to the CIS thus far?

[T77911S]

i love carbs, i love the sound, i love the looks i love the performance! but they can be a pain.
i also love CIS. its extremely reliable, i dont have the computer or O2 sensor. it gets great gas mileage, even with your foot in it. on carbs, you have 6 air correction adjustments, 6 mixture adjustments, 2 idle adjustments and the linkage. plus you have to get the correct emulsion tubes, jets, venturies and so forth. so dont think you will through a set of carbs on and go.


what did you do to the WUR.
what all have you replaced?
do you have a good understanding of the CIS components and what they do
do you have pressure gages
have you checked your pressures
does you car have a pop off valve
do you have 12v to i think it is pin 15 of the CD when the key is in the on position
can you lift the AFM plate. IE is the plunger in the fuel distributor stuck
is the fuse good for the relay
is the freq valve clicking or making a noise
try lifting the AFM plate when it starts to keep it running
if you lift the AFM does the fuel pump run with the key on

[T77911S]

try fuse 18?

[ssrodder]

Had a friend who works on Porsche's over to look at my 82sc. He did the pressure checks and every thing was way off. He said that it looks like the CIS was modified in the past. However, I knew this was a running car prior to it being parked 4 or 5 years ago. He found a two prong plug laying on top of the motor under the air box that was disconnected and taped up. Could not find where it went. It has a brown ground wire and a red with a white stripe wire. He also feels the the auxiliary air valve was removed and plugged. He said it looks like a factory modification, but it should be there on an '82SC. He said the chain tensions were upgraded and there are many new bolts in the exhaust system. He feels since the fuel tank and fuel pump were all gummed up from old gas that both the WUR and the fuel distributor need replacing. He recommended finding a good used CIS unit from a running '82 and replacing just about everything involving the fuel system.
He recommended one other choice. Sell the 3.0 engine and put in a 3.6 and all the upgrades necessary at a cost of about $15,000 to $20,000.
The Weber's sound like a better choice to me.

[Jared at Pelican Parts]

The red/white + brown connector is supposed to be common power to the WUR, fuel pump relay and the Oxygen sensor relay according to the factory wiring diagrams. Without the WUR working, you would have the starting and stalling problem. Maybe check these two relays first? T77911S is also correct. Check fuse no. 18. This powers the oxygen sensor relay.



Sounds like he's trying to make some money off you IMO. The '82 WILL have an AAR. I'm not aware of any factory modification. I would try having the CIS fuel head and the WUR cleaned out by someone who knows these units. CIS is NOT difficult. And it's not difficult to find complete CIS setups removed from cars for considerably less money than carbs.

Carbs are going to cost as much to have them setup right, and even then, you'll get worse mileage, throttle response, and a system inferior to what it came with. Really, spend some time learning how the system works.

[ssrodder]

Wires going to WUR are connected, but the taped up plug was just to the right of the WUR, but long enought to reach into the back of the engine compartment.

[Jared at Pelican Parts]

my bad.

The red/white wire is also common to the WUR. quick check on an SC here...

check the O2 sensor relay and fuse 18. Also, without a AAR, the car would likely have trouble running when cold.

[ssrodder]

OK, took WUR apart tonight. Much cleaner than most carbs I have taken apart. A little black residue where the pin goes in the orifice that is held to the body of the WUR by four screws. I cannot blow thru either the in coming or return lines at that location. Should I be able too? In the Pelican tech article about building a adjustable warm up regulator it mentions a diaphram with two small orifices needing to be completely clear. Is this diaphragm under those four small screws? Is there a secret to removing the wires to get at those screws? How do I get the pin to say in place when I reassemble the unit?
Those carbs are looking better every day.

[EarlySport]

Originally Posted by Jared Fenton

Carbs are going to cost as much to have them setup right, and even then, you'll get worse mileage, throttle response, and a system inferior to what it came with. Really, spend some time learning how the system works.

I beg to disagree...

I also had issues with CIS, and honestly diagnosing it is a PIA. For me it was incredibly easy to bolt on a set of 40mm Webers, order all the venturi's and jets from PMO ( their recommendations based on my engine - early headers and sport muffler ), and bolt it on.

The car has night and day better throttle response than it ever did with CIS, starts and runs faultlessly, and feels like it makes more power. The car hasn't been on a dyno, and had no further tuning. At some point in time I'll do pistons and cams and probably then do some dyno tuning.



Cheers,

[911Rich]

Properly set up carbs do give you better throttle response, they make the most sense with a cam change (and also allow for a more drastic cam whereas cis' design doesn't work well with high lift cams).

CIS is a great stock system and probably the best choice for a daily driver or for someone who doesn't have the patience for carbs.
Any fuel system, be it carbs or injection is going to suffer from a contaminated system especially those systems using a fuel distributor, you should see gummed up/cloged carbs!! Having sat 4-5 years your car is going to have a gummed/sticky fuel dist/air sensor plate piston as well as the WUR, injectors etc. I would place my bet on the Fuel distributor first and ensure that is moving properly, you can access the sensor plate through the airbox filter opening. BUT, before anything, you have get rid of the dirty fuel system otherwise you'll be spinning your wheels and getting more frustrated. Clean everything up then check pressures and carry out your diagnostics. Don't forget a new filter!

[splinterAMG]

Originally Posted by EarlySport

...The car has night and day better throttle response than it ever did with CIS, starts and runs faultlessly, and feels like it makes more power...

There’s no denying yours is a beautiful setup.

ssrodder- a properly functioning CIS will deliver the acceptable driveability you seek.
Best wishes getting it squared away.

[T77911S]

beautiful craig, uh, not craig the car.

there is a screen on top of the WUR, it can get dirty and raise you CP. the 4 little screws hold a diaphrgm on. since you have gone this far, try and get to them and clean all that up.
verify cold CP and warm CP and post.

check that fuse, i think it runs the clock too so it the clock has not been working it may be a sign the fuse is bad.

check the back side of the AFM, there is a connector there and there is a connector on the back of the throttle position switch and there is one on the CSV, also check to make sure one is on the AAR and the WUR. if all of those are connected, you are ok. you may want to pull one just to verify 12v on one of the pins. if it is a flat brown connector, it may not be needed or it went to a fan motor.

if you have replaced a lot of parts, once you get it running, it will be a very maintenance free system.

[T77911S]

look up MCA. he has a link to a LOT of pics of an 82 engine, it may help in seeing what is on the back and how things should be hooked up.