Weber 34 DATA 4/100 carburettor jetting specs for Australian delivered Beta 2000

[Gromit]

My father`s 1979 Beta Coupe 2000 has a Weber 34 DATA 4/100 carburettor fitted which was apparently the standard spec twin choke carburettor for Australian delivered Betas with 2000 engines from 1978/79 onwards. I was having trouble finding the standard jetting specs for this Weber model to compare with what is currently in the carburettor. I eventually tracked down the original Weber spec sheet here (at a cost!). I can provide a pdf of this spec sheet if anyone is interested and would like a copy.

https://classiccarbs.co.uk/product/weber-34-data-4-100-carburettor-factory-jetting-for-lancia-beta-2000-cm-mod-australia-1978

The ex factory Weber 34 DATA 4/100 jetting specs are: primary idle 50, secondary idle 80, primary main 115, secondary main 135.  These specs are the same as those fitted to our 79 Beta Coupe with the exception of the installed secondary main jet which is labelled 120. That seems to be a major discrepancy. I am not sure whether the 110 jet has been modified or drilled out to increase the diameter. My father did have some problems with surging years ago and had someone (an Alfa specialist) in Canberra (Australia) look at the carburettor and make some mods although he can`t recall exactly what was done. It is running on the lean side. We were thinking of trying a larger secondary main jet.

I would be interested to know what other Australian Beta 2000 owners with the Weber 34 DATA 4/100 carburettor are running jetting wise and whether they are happy with their carburettor tuning.

We have had some ongoing issues with hesitation on acceleration, some surging, and lack of power. Some of this may be ignition related. I did just recently check and clean the electrical contacts on the distributor cap which had built up some deposits. That did seem to improve the acceleration smoothness and power delivery to some degree, presumably due to better spark voltage getting through to plugs. Plugs, coil and leads have all been replaced at various stages so are unlikely to be adding to the problem.

We took the car to a local Weber carburettor tuning specialist earlier this year who did all of the usual things: cleaned plugs, reset gap, checked leads and coil. He checked fuel line pressure readings and reported a stable 2.5 psi at idle and under load with the mechanical fuel pump only and 4.0 psi with both mechanical and electric fuel pump running. (Electric pump was fitted and is used for cold start priming only). He cleaned carburettor jets and fitted a new needle and seat (preventative maintenance - the existing one was working ok). Carburettor cleaning was probably not as thorough as others have reported as being necessary so there might still be microscopic crud issues or varnish like deposits affecting jetting. Ignition timing was measured at 14 degrees initial increasing to 36 degrees at 4200rpm (22 degrees mechanical advance). Dyno power output was ok (funny how these intermittent problems never materialise when under diagnostic testing) apart from a slight hesitation between primary and secondary throats.

I am not sure how stable and reliable the nearly 40 year old Bosch distributor ignition pick up and ignition control module is operating. Perhaps the terminal block contacts should be checked and cleaned or sprayed with contact cleaner. I read that suggestion on another thread dealing with suspected ignition problems. I am a bit nervous of doing this in case something breaks (a pin or connection point) rendering the whole system defunct. I gather that the Bosch distributor ignition pick up is virtually impossible to source, likewise the original Bosch ignition module. So we are going to have to explore other distributor trigger mechanism options if and when one or both components fail completely. They may be contributing to the hesitation and intermittent power delivery problems.

My brother`s Fiat 124 spider engine died very recently..he could not start it. He had current at the coil so not an ignition switch problem. He replaced the ignition coil...no effect. He replaced the ignition leads and plugs...no effect. He then tracked down a new Marelli distributor ignition pick up from the US  and found that the old magnetic pick up virtually disintegrated when it was removed. The car started at last with the new pick-up but the ignition timing was way out with the car backfiring and developing no power and had to be reset. It is now going better than ever...so had probably been suffering from a progressively deteriorating distributor pick-up and mistimed engine.  Lucky for him you can still get Marelli distributor magnetic pick-ups!

I guess a healthy dose of carburettor cleaner in the fuel tank would also be a good idea to help dissolve any pesky build up of deposits in the carburettor. We do use premium 98 octane Shell V-power fuel in the hope that the claimed cleaning additives in it will keep the fuel system free of gunk but I guess an extra burst of additive now and then might be of benefit.

[Nigel]

Hi Mr Gromit!
I have just acquired a 1984 HPE originally supplied in Australia,hence it's carb-fed. I haven't yet confirmed that it still
has the 34 DATA carb,but I suspect it does.

My query is about the emmisions equipment fitted.

There is a black-plastic box-shaped thing mounted below the brake master cylinder and a white thing [pump?] mounted
under the left-hand brace bar,connected to a fast-idle check push-button, both of which have fuel hoses connected.
Do you know what these things do and how the system works?
And more importantly, with the existing carb work fine if I delete all this 'extra' equipment?

Ideally, all I want to have is an electric pump,a pressure reduction valve [if necessary] and a return feed to the tank
i.e. basically a standard set up.

Nigel [UK]

[Nigel]

Mr Gromit,
In addition, if possible,can you email that spec sheet?
I will be forever grateful!
ntpeart at btinternet dot com
Best regards

Nigel

[Neil-yaj396]

Nigel - I don't think that 'Gromit' has posted on here for some time.

[rossocorsa]

https://www.amazon.co.uk/photos/share/C3Y1D2oNqsfk9jyG5Kxsc0fv44h1vO2VmGQW1U7mMz6

https://www.amazon.co.uk/photos/share/dn5ZdYHjgow5EVCK1p0pNWL82F7albQVG3c4uuQXML6

Not sure if this is any help, not necessarily Australian market. There's a line of thought in any case that suggests you may need to adjust jetting slightly to suit modern fuels

[Gromit]

Hi Nigel,

Apologies for not responding sooner. Notifications for this thread posting ended up in my Hotmail junk folder...which I tend to check infrequently.

I`ll send you the Weber carby spec sheet as requested.

Re your queries identifying Australian delivery carby equipped Beta fuel system components and whether they can be bypassed, I am not sure I can be of much assistance. I had a quick look under the bonnet of my fathers`s Beta Coupe today in the garage at my mother`s house where it currently resides. I saw the black canister below the brake master cylinder. There was a braided hose going from the top of the unit back to the inlet manifold. I could not see much else from the top looking down. Not sure if that is a vacuum hose or something to do with returning collected fuel vapour. I could not see any "white thing [pump?] mounted under the left-hand brace bar, connected to a fast-idle check push-button". I probably need to get the car out into the open to have a proper look.

I was going to suggest that you ask Rossocorsa whether he could post a copy of the complete Australian delivery Beta carburettor fuel system from the Lancia factory parts catalogue. This should provide an exploded diagram of the fuel system components and a brief description of each component. From that it should be possible to identify what each component does and what can safely be bypassed or removed. Rossocorsa kindly provided a photo from the parts catalogue in a previous thread dealing with the Australian delivered Beta fuel tank inlet and venting hose arrangement. Here is the link to the photo to show you what I mean and thread from which it originated:

https://photos.google.com/share/AF1QipOSrGOgXtMhkJ9lZx9aLS9_HufuVcV39tGo68byFCpRVmXkpLUqATLePC-oXRvcWw?key=OVhRcVQxU1lwRTI2YWFIQlg1b0lrQjdGTUZJRGln

http://www.betaboyz.myzen.co.uk/forum/index.php?topic=3692.msg24973#msg24973

Other forum members based in Australia might also be able to enlighten you further. I was going to suggest you start a new thread to have a greater chance of attracting some interest and a response from them but this posting might elicit some further interest and advice especially if there is an appropriate posted photo from the relevant factory parts catalogue to help you identify the system components.

Good luck!

Cheers, Andrew

 

[rossocorsa]

As Nigel's HPE is a series 4 or S2FL2 I need to have a look at the microfiche, unfortunately microfiche isn't so well illustrated but when I've time I'll have a look. I'll check the earlier parts book too but they might not correspond.

[Gromit]

Thanks Rossocorsa, very helpful as always.

I suspect that the Australian delivered series 4 HPE will be virtually the same fuel system wise to the earlier series 2 FL version as all Australian import Betas were carburettored models only ie no fuel injected versions which were a feature of 2 Litre UK, European and USA cars from 1981 onwards. So the parts catalogue with its better diagram illustration of Australian delivery carburettor fuel system Betas would probably be the best starting point.

The local Fiat and Lancia importer into Australia was apparently paranoid about the potential lack of reliability of the then new fuel injection technology which might  result in it being swamped by warranty claims (wrongly as it turned out), and requested carburettored only RHD Betas from the factory right up until production ceased.

[rossocorsa]

You're in luck I already had this one photographed

https://www.dropbox.com/s/6aj56leeis3pww0/43fuel%20system.JPG?dl=0

[rossocorsa]

Relevant as it has Aircon I think (?)

https://www.dropbox.com/s/olh7fktwceevtfc/47air%20cleaner%20control%20autoandaircon.JPG?dl=0

[rossocorsa]

https://www.dropbox.com/s/29y0y6dbo06k3f3/68manifolds%20%281%29.JPG?dl=0

[Gromit]

Unfortunately neither photo shows any of the under bonnet anti-pollution/emissions components fitted to 2L Australian delivered carby Betas. Do you have any photos of the engine bay fuel vapour capture system or other emissions components linked to the carburettor, air intake or inlet manifold?

[Nigel]

Andrew [gromit] , many thanks, sorry i'm only here now, i must sort out email,as like you,
the notifications go to junkmail!

The square black plastic box under the brake master cyl,is,i now think, part of the air-con system,as it's directly
connected to the heater on/off valve located above the exhaust manifold. So that will remain.

Alan, thanks for those links to parts pages. I'll take a much closer look soon.

I'll try posting a pic of the 'white-plastic-pump-thingy' and the push button marked 'fast-idle-check',
i think though, that one of Alan's pics shows that.

Cheers all, Nige

[Alastair Watson]

Hello, Lancia People.

I’ve spent literally hours and hours searching the ‘net for info on the Weber 34 DATA and this is the only place it’s even mentioned.

Can someone please tell me where the idle mixture screw is on said carby?

It isn’t the same place as the 32 DMTR is (rear 0f carby, centre of base plate).

Thanks,

Alastair.
(‘76 Fiat 128 3P, ex-Uk ‘77 X1/9 & ‘75 Mitsubishi Galant hardtop)
Tasmania, Australia.

[Gromit]

Alastair, I just revisited this thread and noticed your postings. I do not get any notification of new posts in my email but I note you have sorted out your carburettor issues in this thread, which is good news:

http://www.betaboyz.myzen.co.uk/forum/index.php?topic=5094.0
 
Just for the record, I ended up increasing the primary choke idle and main (original spec) jet sizing from 50 to 55 and 115 to 120 respectively, which is within the recommended Weber spec sheet adjustment tolerances (+5), with no changes to factory spec air corrector jet sizing. This has reduced but not entirely eliminated light throttle hesitation, fluffiness and delay in acceleration. I tried the larger idle jet size first with little discernible improvement and then changed the main jet size as well, which made a noticeable difference. I am reluctant to increase the jet sizes further without any CO exhaust gas analysis to avoid having unburnt fuel in the combustion chamber and risk excessive cylinder bore wear from residual unburnt fuel scouring the cylinder bore oil film lubrication.

The secondary choke main jet as fitted was 120 which is three sizes smaller than the Weber factory spec of 135 for this 34 DATA 4/100 Aust 2 Litre Beta spec carburettor. I fitted the correct 135 spec jet and this has, not surprisingly, transformed the top end performance which is now smooth and progressive above 3000 rpm instead of the previous strangled fuel starved performance. No idea how the 120 sized secondary choke main jet came to be fitted to the carburettor. My father`s memory is now too unreliable to recount the car`s history in this regard!  

Note that Australian unleaded fuel does not mandate a 10% ethanol component, so jetting spec requirements between UK and Australian Beta engines will probably differ to account for the lack of ethanol in Australian fuel, (which is not E10 fuel at any rate). Other UK Beta forum members have reported on successfully implemented larger increased jet size changes to account for E10 fuel usage which was not around when the carburettor running specs were first determined by Weber and Lancia.

Some Beta owners have reported smoother and hesitation free acceleration following a complete professional distributor strip down, cleaning and lubrication, after addressing the usual suspected carburettor and fuel supply issues, (thorough cleaning and servicing of carburettor, fuel lines, fuel filter, fuel pump performance and delivery line pressure and flow rate etc), and usual ignition service items, (spark plugs, plug leads, distributor cap and rotor), and ruling out ignition coil or Bosch electronic ignition module failure, (for ignition points free post 1978 cars), without solving the performance shortcoming issues. I gather there can be a problem in old Beta distributors with the distributor ignition advance centrifugal magnets sticking and not adjusting the ignition advance smoothly during engine acceleration, which can be remedied by a distributor strip down, clean and lubrication overhaul, replacing any worn parts at the same time.

Short of that, putting a few drops of engine oil occasionally on the distributor mechanism after removing the rotor button, is supposed to be good, (but often forgotten), distributor lubrication maintenance practice.

Full 34 DATA 4/100 Weber carburettor specs:

Varianti
Carburettor 34 DATA 4/100 LANCIA
Part Number 18890.179 Beta 2000 - CM
Mod. Australia -1978
Calibrated Parts Recordings
1* cond. 2° cond. Value
Choke 25 27 Floating level :
Centering 4 4 With gasket (BRASS) mm
Main Jet 115 + 5 135±5 With gasket (POLYANSI) mm 7
Air corrector jet 170 + 10 220 + 10 Without gasket (BRASS) mm
Emulsion tube F30 F30 Without gasket (POLYANSI) mm
Full power gasoline bush 70 From the carburetor tray plane mm
Full power air bush Excursion max. float mm 43
Supercharged Gasoline bush 110±10
Supercharged Air Bush 0 Acceleration pump
Bore/Tube Supercharger mixture 200 Capacity 10 pumped complete and total cm3 11,7+17,5
Supercharged mixing bushing at the centring Butterfly Opening pump Recording mm
Recording main Butterfly
Idle Jet 50 + 5 80+5 Opening 1 ° Duct start 2 ° duct mm 7,7
Minimum air bushing 110 + 10 70 + 10
Irreversibility hole 100 Dash-pot
Minimum register hole 155 Butterfly Opening with contact tip mm
Minimum mixing bush 200
Sonic Minimum Air bore/bushing Manual start
Minimum air hole derivation Mechanical Sgolfamento mm
Hole Mix Minimum derivation Fast Minimum mm
Sgolfamento Pneumatic mm
Jet Pump 50 Sgolfamento Pneumatic minimum mm
Pump Drain/exhaust spill valve jet 0 Sgolfamento pneumatic max. mm
Pump Suction and discharge valve Rod Full Start Double. 61287.
Air Pump Jet Starter Spring Double. 47605.
Pneumatic pump discharge
Diaphragm pump Double
.
47407.048 Automatic start
Recording Game Butterfly Starter mm
Mechanical Sgolfamento mm
Jet Starter Fast minimum on the stem mm
Start Air jet Fast Minimum mm 1,1+1,2
Fast Minimum cam timing mm 6 3° grad.
Needle valve Double
. 79507.175 Game bushing-Lever sgolfamento mm 0,5
Sgolfamento Pneumatic minimum mm 5±0,5
Recirculating Fuel Hole 100 Sgolfamento pneumatic max. mm 8±0,5
Fixed index marking
°< 65° ±30'
Progression Holes T, 80 100 Mobile Index Registration mm 0
100 100
T3 100 Bimetallic Box Double. 57804.190
L 100 Sgolfamento capsule Spring Double. 47600.092
T5 Starter Spring Double. 47605.005
Slot Progression Starter Spring Double. 47610.
Main butterfly inclination 78° 78°
7-1979 Weber carburetors 40134 Bologna - Via Timavo 33
Weber Spa Company Phones: 051 417995 / 434205 / 437403
Telex 510119 Web Bo-I