1.4 Weber carb question

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gregsx2
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Joined: 29 Dec 2013 04:31 pm

Re: 1.4 Weber carb question

Post by gregsx2 » 22 Feb 2014 09:18 pm

mac wrote:Assuming the choke pull off diaphragm is not punctured or otherwise damaged it can certainly be re-used no problem (they rarely are damaged) that certainly is a cheap kit! - in the UK something similar would be £30 - £35 GBP.

As for cleaning - I usually say "magic" or "trade secret" but actually unless the grime is very stubborn I find White Spirit (also known as Turpentine Substitute) is very effective. I tend to dismantle the unit and soak the components over night
and use small brushed like toothbrushes.
If you do this though I highly recommend you use a compressed air line to carefully blow out the passages and fine drillings after the overnight soak.

Mac.
Thank you Mac, I'm very grateful. :wink:

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mac
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Location: Needham Market U.K.

Re: 1.4 Weber carb question

Post by mac » 22 Feb 2014 10:08 pm

My pleasure,
Any further questions - just ask.

Mac.
88 5door Redline 1.7 52k - 19 XC60 Momentum Pro D4 AWD 17k
1950 pair of legs that don't work very well.

gregsx2
Posts: 16
Joined: 29 Dec 2013 04:31 pm

Re: 1.4 Weber carb question

Post by gregsx2 » 23 Feb 2014 03:01 pm

mac wrote:My pleasure,
Any further questions - just ask.

Mac.
I couldn't wait.
WP_20140223_13_30_29_Pro.jpg
WP_20140223_13_30_37_Pro.jpg
WP_20140223_13_30_55_Pro.jpg
The choke pull of diaphragm not in good condition :( Can I buy separately?

But i do a mistake. I wont separate the primary and the secondary jets. Which pairs? 1st: 122-190 and 2nd: 137-195?
WP_20140223_14_20_13_Pro.jpg
jets

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mac
Posts: 1403
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Location: Needham Market U.K.

Re: 1.4 Weber carb question

Post by mac » 23 Feb 2014 03:41 pm

Well - your full load enrichment diaphragm is definitely split!.
The choke pull off actually does not look too bad - the "crumpling" is normal - the key is does it leak?

When you reinstall the full enrichment device cover make sure it's positioning is correct - the W symbol does NOT sit horizontal.

Image

Jets - Primary Main would be 122 and Secondary Main 137
Primary Air Correction would be 195 and Secondary AC 190

If you PM me your name/address I'm sure I can find you a choke pull off diaphragm - happy to help.

Mac.
88 5door Redline 1.7 52k - 19 XC60 Momentum Pro D4 AWD 17k
1950 pair of legs that don't work very well.

gregsx2
Posts: 16
Joined: 29 Dec 2013 04:31 pm

Re: 1.4 Weber carb question

Post by gregsx2 » 23 Feb 2014 05:42 pm

mac wrote:Well - your full load enrichment diaphragm is definitely split!.
The choke pull off actually does not look too bad - the "crumpling" is normal - the key is does it leak?

When you reinstall the full enrichment device cover make sure it's positioning is correct - the W symbol does NOT sit horizontal.

Image

Jets - Primary Main would be 122 and Secondary Main 137
Primary Air Correction would be 195 and Secondary AC 190

If you PM me your name/address I'm sure I can find you a choke pull off diaphragm - happy to help.

Mac.
Thank you. :)
choke pull-off maybe usable. I live in Hungary. I think the post little expensive :)

I have 2 copper sealing washer. Where are they from? :oops: Under the acclerator pump jet?
And have 2 O ring. 1 on the pneumatic choke pull off device vacuum port and 1 under the secondary idle jet?

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mac
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Location: Needham Market U.K.

Re: 1.4 Weber carb question

Post by mac » 23 Feb 2014 06:04 pm

If you find the choke pull off needs replacing let me know (don't worry about postage).

The two copper sealing washers fit on the "banjo" bolt either side of the accelerator pump jet.
The two 'o' ring fit just as you say.

Not as difficult as it seems is it!

Take care - Mac.
88 5door Redline 1.7 52k - 19 XC60 Momentum Pro D4 AWD 17k
1950 pair of legs that don't work very well.

gregsx2
Posts: 16
Joined: 29 Dec 2013 04:31 pm

Re: 1.4 Weber carb question

Post by gregsx2 » 24 Feb 2014 06:24 pm

I finished the reassembly, special thanks to Mac. sm4 (but maybe need me a new choke pull-off :( )

I Screw the idle mixture screw in fully and back it out by two turns then more two or three (I don't remember) because i hadn't got smooth idle on operating temperature. It's not too much?
The car is more powerful than before but isn't perfect (compared to Skoda, 72Hp vs 68Hp) but i don't know.. sm1

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mac
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Location: Needham Market U.K.

Re: 1.4 Weber carb question

Post by mac » 24 Feb 2014 09:22 pm

To help you decide if you need more work -

The choke pull off diaphragm only takes effect when on full choke - it slightly opens the choke flap when just opening the throttle to introduce a little extra air under full depression conditions. As soon as the engine starts to warm up and you start to "push the choke in" the pull off no longer operates.

The initial start point for idle mixture screw is fully in then back out two turns - this should allow the engine to run. The idle mixture is then set by moving the screw (generally further out) until you obtain the fastest/smoothest idle - then correctly set the idle speed using the throttle stop screw (idle speed screw).
If using a CO% meter set the idle mixture to around 2.5% - then set idle speed correctly. Assuming all is well the engine will idle happily at 1.0% but 2.5% is much better.
The idle mixture is however just that - mixture at idle - the engine is running on the idle circuit only and the idle screw has no effect on the general running of the car.

If the car starts and runs well, with no hesitation, and with a stable idle the chances are that you won't improve things (power etc.) with the fixed jets and emulsion tubes fitted. Things could probably be "improved" by changing jets (slightly larger main jets might help) but without a range of jets and the use of a rolling road you could do little but "try things and see".
Don't forget your perception of power is affected greatly by gear ratios, ratio spacing and throttle progression.

Mac.
88 5door Redline 1.7 52k - 19 XC60 Momentum Pro D4 AWD 17k
1950 pair of legs that don't work very well.

gregsx2
Posts: 16
Joined: 29 Dec 2013 04:31 pm

Re: 1.4 Weber carb question

Post by gregsx2 » 25 Feb 2014 07:48 pm

mac wrote:To help you decide if you need more work -

The choke pull off diaphragm only takes effect when on full choke - it slightly opens the choke flap when just opening the throttle to introduce a little extra air under full depression conditions. As soon as the engine starts to warm up and you start to "push the choke in" the pull off no longer operates.
I have smooth idle on operating temperature and the engine run correctly, but when i use choke on lower temperatures dont have a smooth idle, not better with more or less choke. Maybe the mixture is too rich ?!
mac wrote:If the car starts and runs well, with no hesitation, and with a stable idle the chances are that you won't improve things (power etc.) with the fixed jets and emulsion tubes fitted. Things could probably be "improved" by changing jets (slightly larger main jets might help) but without a range of jets and the use of a rolling road you could do little but "try things and see".
Don't forget your perception of power is affected greatly by gear ratios, ratio spacing and throttle progression.

Mac.
Thank you Mac, I will try different settings. But it will never be a race car :)
Maybe later I will open a car presentation topic. 8)

Thank you for your help, i have failed without you sm4

(second time I will do better this :twisted: )

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mac
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Location: Needham Market U.K.

Re: 1.4 Weber carb question

Post by mac » 25 Feb 2014 08:25 pm

With carburettor'd engines mixture control during the warm up phase is never exact - generally relying on a reduction of air supply by closing the choke flap.

No only does this reduce the air but also increases manifold depression drawing excess fuel via the main jets.
IN THEORY with a closed throttle (at idle) the engine is running on the idle circuit only and will inevitably be weak when cold (so a "perfect" idle is never perfect during warm up).

That having been said, with a closed choke flap there is always a higher depression drawing fuel so in reality the mixture ends up rather richer than ideal. This is compensated for by the choke cam acting on the throttle linkage to open the primary barrel throttle disc to raise the idle to compensate - the more the choke is closed, the more the throttle is opened.

The relationship between the choke and throttle is adjusted by a screw on the throttle linkage acting on the choke cam. For a given choke setting the throttle opening and hence idle speed can be adjusted. It could well be worth "playing" with this to improve the cold running performance.

The other possibility is that the choke pull off diaphragm is not operating, allowing "over choking". You can check this by removing the top of the air cleaner so you can see the top of the carb. Close the choke fully, start the engine and you should see the choke flap open slightly. If the flap does not move the pull off mechanism is not functioning correctly.

I'm glad you think I've been able to help, but don't forget the work has all been yours - I've just mainly confirmed your thoughts.

Mac.
88 5door Redline 1.7 52k - 19 XC60 Momentum Pro D4 AWD 17k
1950 pair of legs that don't work very well.

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