Weber 34 DATA

[Alastair Watson]

Hello and thank you for admitting me to your forum.

It was the only place that I could find any reference to a Weber 34 DATA at all.

At this point, I should confess that the carby is not currently gracing a Lancia but is instead fitted to my 1976 Fiat 128 3P, running a 1.3 litre engine w/ a port-matched and polished inlet manifold, a mild cam, electronic ignition and extractors. 

I hope this is ok w/ you. 

I’ve done a rough job rejetting the carby, based on info on the X-Web for a car w/ similar specs. 

It’s not perfect but it’s running ok.

I also went to adjust the idle mixture but can’t see where the screw is - it doesn’t seem to be in the same place as it is on the 32 DMTR that was on the car. 

The equivalent spot of the DATA seems to be a shallow and blind hole, without any thread, which is why I don’t think the screw’s meant to go there.

Is anyone able to point me in the right direction, please?

Cheers,

Alastair,
Tasmania, Australia.

[HFStuart]

I think we'll allow a cousin to join in! Especially as a decent proportion on here will read 3P and think 'oooh, nice!'

Looking down on the carb the idle mixture screw should be roughly as indicated by the arrow in the side of the carb body  - almost in the baseplate.  I say should as there are a LOT of variants on the DATR / DMTR. A couple of photos of the carb from either side with the air cleaner off would help.

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 Inlet manifold

[smithymc]

Another 3P fan here.

Mark

[Nigel]

Hi all,
Referring to Stuarts drawing, on my 34 DATR the mixture screw is opposite
to the marked arrow, but as said, many variations exist.

Nigel

[Alastair Watson]

Thanks, HFStuart, Mark and Nigel.

I had been looking for the screw on the baseplate on the opposite side to the inlet manifold (the back) rather than the left and right sides.

It’s hissing down here at the minute (not an ideal summer’s day!) but I’ll be checking out both suggested locations when it’s dry again.

I’ll try to get photos, too.

Will update with outcome.

Assistance much appreciated!

Cheers,

Alastair.

[Nigel]

Hi Alistair,

I've now dug out my Aussie carb and hopefully these photos will
clarify.
It is possible that this location is capped with
an alloy plug. This was a factory action to prevent tampering with the
emissions settings but they are normally long gone.

[Alastair Watson]

Thanks, very, very much, Nigel!  That’s extremely helpful.  Yours is the exact same model as I have.  Mine is capped.  I think that’s all I need to know now.  I can’t imagine that it’s super difficult to uncap the hole.  However, I think it puts the job into the specialists’ sphere, as there’s too much mucking about for me to do it:  uncapping, knowing which screw to use, sourcing parts, etc … .   The carby needs to be rejetted anyway, so I’ll get it done professionally. 

[JohnFol]

Big fan of getting them adjusted by someone who knows what they are doing but if you know the jet sizes, it's a very easy job and cheap. I got mine (plus emulsion tubes / air correctors ) from these people

https://www.dellorto.co.uk/

Swapping them over is measured in minutes not hours

[Nigel]

Hi Alistair,
There will be an adjusting screw behind the plug if
you're feeling adventurous. The plug will come out with a
sharp-pointed thing, it's quite soft.

Cheers
Nigel

[Alastair Watson]

Thanks, John.

The physical swapping isn’t what scares me; it’s knowing what’s likely to work on my slightly modded 1.3 Fiat v the way it’s set up for a 1.8 or 2.0 Lancia.  I got it going reasonably well using jets, emulsion tubes and correctors I already had, based on info from an X1/9 forum, but now it’s specialist time, especially seeing the mixture screw’s been “hidden.”

[Alastair Watson]

Hi, Nigel.

I’m sure you’re correct but I think it’s pro-time so that the carby can be “personalised” to the car it’s on. 

I was going to have a crack at the mixture if I could find it (get it running a bit smoother / learn something).

Too many variables now - jets, e tubes, correctors - for an amateur like me, I’m afraid. 

Thanks again for your help.

Cheers.