Are my Weber 40 IDA 3Cs matching ..?

[NigelJones]

Dear all,

I have a newly rebuilt 2.7 RS engine. The engine builder sold me a pair of used Weber 40 IDA 3Cs.

I now have the engine in the car and we are having some tuning challenges .... the workshop (not the engine builder) advise that the carbs were not refurbished and have too much slop to be ideal. They are recommending that I have the Webers rebuilt professionally.

An acquaintance has offered me a NOS pair of 40 IDA 3Cs so I have started checking part numbers to ensure compatibility. My current carbs are marked - WEBER TIPO 40 IDA3C and 979 below. Reading online it seems that these should be a pair with 3C for the passenger side and 3C1 for the driver's side (on a LHD car) but I have a matching pair of 3C (i.e. no 3C1).

Do I have a mismatched pair ... does this explain why the car is running poorly? Could one of the 3C be modified to be a 3C1 ... or is it just plain mismatching?

The NOS carbs have been in dehumidified storage for about 12 years ... I have not yet inspected but can someone guide me on what to look out for before doing a deal? Obviously, don't want to buy NOS and then have to refurbish ....

Thank you,

Nigel Jones

[T77911S]

looks like you have 2 for the same side.

don't think it would effect how it runs, but could be wrong.
great info here.

Performance Oriented

[NigelJones]

Thanks, I had read that useful article. The fact that it explains that the carbs are handed and which one goes on which side suggests that there must be some reason for pairs (otherwise why manufacture two types)?

The replacements that I am being offered are a matching pair .... So am trying to figure out if I can swap a pair of 3Cs for C and a C1.

Nigel

[Porsche 2]

I have observed on mine the difference between C And C1 is a matter of which end of the throttle shaft has the lever attached, and thus the longer of the "in-line shafts, in order to accommodate stock throttle linkage.

[1QuickS]

A "C" can be re-configured as a "C1" but you need a "C1" throttle lever arm. The other difference between C & C1 is the location of the main jets but this is not an issue of importance.

Re-configuring is not hard but removal of shafts requires care to not bend them when applying force to loosen the throttle valve "pinch" screws and then the re-assembly is exacting in getting throttle valves aligned in the bores and in setting axial end-play correctly.

Another item needing re-configuring is the location & orientation of the lever arm mounted on the long throttle shaft that is used to operate the accelerator pump. This requires drilling a new 2mm diameter hole in the throttle shaft.

Another item: the short throttle shafts are handed as well so re-configuring what you have or replacement is required.

[NigelJones]

1QuickS,

Perfect, thanks, this is the guidance that I was after .... so I am arranging to get the matching pair of NOS C/C1s taken out of storage and will take a look at them to see if it is easier to swap to a matching pair (rather than rebuilding my non-matching pair).

Your guidance is helpful to understand what might have been done to swap the 2Cs into a C+C1, but if the workshop is unbolting the old set and bolting on the NOS, will there be any special work required to go back to 'correct' C+C1 ... assuming that the C+C1 set is complete?

Nigel

[1QuickS]

Not sure I understand the question but if you are asking about jetting then there is nothing within the carbs that would prevent swapping jetting from your "C"s to the C & C1 carbs.

Have a good look at the new set. "Made in Italy" is what you would like to see on each body. If they are NOS then all should be good but you might want to replace gaskets for the accelerator pump as these need to be fresh.

Also, the castings for the bodies evolved over the years so look for common casting details on the exterior of the bodies; however the internals are all the same so early & newer IDA3Cs and IDA3C1s are equivalent for fuel delivery performance.

[NigelJones]

Hi 1QuickS,

Apologies if my question was poorly phrased ... let me try again ...

Based on your kind guidance, it seems that someone converted a C to a C1 ... I am now trying to work out if I can have the shop unbolt the non-matching pair and swap with a matching pair ... ? I am hoping to get hold of the NOS set in coming days and will check if there is a 'Made in Italy' on the casting. I am wondering if the NOS set will have all new linkages or whether the existing linkages need to be transferred across (and, if transferred, whether they will have been altered as part of the use of a non-matching pair).

Hopefully a little clearer now?

Nigel

[1QuickS]

If the NOS set is comprised of C & C1 then you are good to go.

[NigelJones]

Thank you for the help on this.

[NigelJones]

Sorry folks, it seems that I may need a little more help on my webers ...

Yesterday I picked up the 40 IDA 3Cs from my acquaintance and visited the workshop to take a closer look. Here is what we managed to find out:

- these are NOS, from the main Singapore importer/ distributor. They had been on the shelf for some while when the shop closed 12 years ago and my acquaintance acquired and then stored the parts. On this basis, I guess that they are at least 15 years old, but look to be in good condition with no obvious blemishes

- unfortunately, the box deteriorated long ago and so we have no idea what the configuration is ... this is the issue

- source marking are not clear ... there is no "made in Italy" and no "made in Spain". Does this make them Carters? Of course, they could be fakes but seems unlikely as they came through the main importer/ distributor

The workshop does not want to start dismantling to try and work out what the configuration is and guide me that whilst they are 40 IDAs, they cannot tell what the venturi or jetting is ... so they recommend sending them overseas to be completely dismantled, checked and reconfigured (if required)

- we had a long debate whether it is better to refurbish the existing, non-matching webers or dismantle, clean and reconfigure (if required) the matching NOS. We are leaning towards using the NOS as they are matching and never used (so should be better than refurbishing...)

On this basis, I have a few new questions:

- can I assume that any good refurbishment shop will have any new parts (such as jets) that are required to reconfigure (if required) or should I send the old webers so that they can take any parts (if they need to)?

- can I assume that if I provide detailed engine specs the carbs can be set up on the bench (i.e. intake and exhaust port sizes, compression ratio, camshaft type, distributor type, exhaust and designated road use) and then just final fettling done once on the car

- any trusted shops that can be recommended? I am guessing that readers here are primarily from the US but if I am couriering from Singapore it makes no difference if I go to the US, UK or Australia (which I think are the likely places to find a specialist).

Many thanks,

Nigel Jones

[juanbenae]

I was wondering after reading this a few times as it's been updated what were the symptoms that made the original set "slop(pie)"? were there any specifics that were noted?

what was done to them prior to being set and how old were they? there is a great opportunity for them to be worn out, but if they'd sat for a few years they could be fine and just need a simple going through.

seems like you could get your current set rebuilt with less headaches than this set you are contemplating...
'

[NigelJones]

Hi Juan

Thanks for the input.

The existing webers were sold to me by the engine builder. He explains that he did do some refurbishment (gaskets and seals) but he is an engine builder not a weber specialist. He thought that the set up was ok when road testing in the UK.

Once the car arrived in Singapore there was a hot restart problem, a plug fouling issue and the engine was very lumpy and never ran smoothly. We improved the spark with a modern CDI box but it did not solve the problems. Then the workshop started looking at the carbs and found that some of the banks were either flooding or getting no fuel at all. They purchased a rebuild kit and managed to get one side running reasonably OK but on the right hand side (looking into the engine bay) they cannot get the middle bank to run at all ... they believe that it is no fuel.

They can do much of the work in Singapore but there are very few cars with webers here and I sense that they are getting to the edge of their patience .... they cant figure it out and don't want to try and rebuild something as unusual as this.

Nigel Jones

[1QuickS]

NOS set should be good but would need new accelerator pump diaphragms at least.

You need a shop that can deal with carbs...damn few of those left.

If carbs on car were reasonably jetted then the jetting can be swapped into the NOS set.

Probably the idle circuit & supply galleries are plugged on the old set. Simple "blowing carb cleaner through the passageways" will not get the "Hidden Gallery" cleared. I say "Hidden Gallery" as that one is sealed with lead plugs and blowing it out is not readily obvious. I offer a couple of procedures dealing with this on my website (Look for "Hidden Galleries"): Performance Oriented

I doubt many shops want to turn off their computer diagnostics to mess with archaic Webers.

[NigelJones]

1QuickS,

I had not realised that it was your website that I have been studying .... now I understand why I am getting such detailed guidance from you. Thank you.

I think that you are guiding me to use the NOS and get them checked (new accelerator pump diaphragms at least) ... did I read that correctly?

Thank you for guiding on the likely source of issues on the old set (idle circuit & supply galleries are plugged...).

I think that it is likely that the old set was jetted correctly, but I cannot assume so. The engine builder I trust (as an engine builder) but he rebuilt the 2.7 and then sold me a separate set of used weber (which I lightly refurbished) ... so the old weber set was not previously running on this 2.7 before it was rebuilt. The 2.7 was taken from a later car, rebuilt for a 1973 RS and carbs added. On this basis, I am thinking of asking someone who really knows what they are doing to check the NOS and use new jets for the detailed engine spec (that I can provide). Are new jets etc readily available or should I be planning to pull the jets from the old set to send over with the NOS?

Sorry, so many questions...

I see from your website that you are not accepting work right now. I appreciate that it might be a sensitive question ... but is there anyone else that you can recommend to do this work (and recognise that this might be better answered via PM).

Thanks again.

Nigel Jones

[1QuickS]

Parts for Webers are readily available.

If you need jetting recommendation for a 2.7RS type of build then please contact me via my business email address on my home page, it is easier for me to provide personal info.

Cheers,

Paul Abbott
Performance Oriented