Float level ? S1 4.2 does not start

Technical advice Q&A

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Durango2k
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#41 Re: Float level ? S1 4.2 does not start

Post by Durango2k » Sun Mar 21, 2021 6:25 pm

Here‘s the U1 photo I promised. Hope it gets through.

These are longer I think, and the tip is different to the UM. I tried to measure the diameter on top and tip, and they differ as well.


Image

Image
Jag E '66 S1 2+2, 74’Citroen DS 23 Pallas iE, 73’ Citroen SM 3.0, 75’ Concept Centaur MK1, 54’ Citroen 11 BL, 71‘ Velosolex, 88‘ Unimog U1650

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bitsobrits
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#42 Re: Float level ? S1 4.2 does not start

Post by bitsobrits » Tue Mar 23, 2021 1:21 am

That's one scabby looking needle, like maybe a homemade profile? Though wrong needles shouldn't keep you from getting the car to start, if it's so far wrong there is no appreciable clearance with the jet even with the choke engaged then I suppose it's possible the needles could be the issue. In any case, I would start with new, correct, needles.
Steve
'65 S1 4.2 FHC (early)

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Durango2k
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#43 Re: Float level ? S1 4.2 does not start

Post by Durango2k » Fri Mar 26, 2021 6:32 pm

Tried to start it today, and it did not - until I unscrewed the dampers on the domes. Then instant success.

What would be a remedy for this - where to look ? Does it mean „worn pistons“ so „not enough vacuum“ above them ? Or too strong springs, or anything else I should look at ?

I drove it today on the yard. Had to double - clutch first time, and boy did that car go.... my son said instantly after the round he‘s scared of it and its a decent widow maker...

Carsten
Jag E '66 S1 2+2, 74’Citroen DS 23 Pallas iE, 73’ Citroen SM 3.0, 75’ Concept Centaur MK1, 54’ Citroen 11 BL, 71‘ Velosolex, 88‘ Unimog U1650

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MarkRado
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#44 Re: Float level ? S1 4.2 does not start

Post by MarkRado » Sat Mar 27, 2021 5:18 am

Get yourself a copy of the SU workshop manual, everything in there.
Are valve timing +clearance, ignition timing, plug gaps spot on? Jet height below bridge 1,6mm (4.2) resp 1,1mm (3.8) as a starting point.
Mark
1963 OTS 880436

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Gérard A110
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#45 Re: Float level ? S1 4.2 does not start

Post by Gérard A110 » Thu Apr 01, 2021 3:32 pm

Hi, at first i thought the bees had made their nests in the fuel lines, but i see than no.
For setting, the oil into the damper above the carburator bell must arrive 1 cm before the top. No more.
The 3 jet neddles 1.5mm lower than the top.
It must work, regardless of the spring or bell tighness!.
E ots 1962, mk2 3.8 1964, SM 1970, A110 1970, A310 1973, Grégoire 1954

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Gérard A110
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#46 Re: Float level ? S1 4.2 does not start

Post by Gérard A110 » Thu Apr 01, 2021 3:42 pm

And for the synchronization balancing betwen the 3 entrances (gates?) if you have not one balancing tool,
use simply one rubber hose ( 1m.) + one funnel .
Apply the funnel at your ear and the hole of hose at the air entry.
You can easy ear the difference of suction, and adjust the big screw for each air.
E ots 1962, mk2 3.8 1964, SM 1970, A110 1970, A310 1973, Grégoire 1954

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Durango2k
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#47 Re: Float level ? S1 4.2 does not start

Post by Durango2k » Thu Apr 01, 2021 5:52 pm

I have the weber tool / for the SM...I‘ll use it.

Currently I have ATF in the carbs, and not SU‘s own oil. And I‘ll check for the 1.5 mm jet height below the bridge.

Carsten
Jag E '66 S1 2+2, 74’Citroen DS 23 Pallas iE, 73’ Citroen SM 3.0, 75’ Concept Centaur MK1, 54’ Citroen 11 BL, 71‘ Velosolex, 88‘ Unimog U1650

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Gfhug
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#48 Re: Float level ? S1 4.2 does not start

Post by Gfhug » Thu Apr 01, 2021 8:20 pm

Carsten, you can use regular engine oil in the carbs.

Geoff
S2 FHC Light Blue
S2 OTS LHD - RHD full restoration

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#49 Re: Float level ? S1 4.2 does not start

Post by Durango2k » Thu Apr 01, 2021 10:47 pm

That would be SAE20W50, then ?

Carsten
Jag E '66 S1 2+2, 74’Citroen DS 23 Pallas iE, 73’ Citroen SM 3.0, 75’ Concept Centaur MK1, 54’ Citroen 11 BL, 71‘ Velosolex, 88‘ Unimog U1650

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#50 Re: Float level ? S1 4.2 does not start

Post by Gfhug » Fri Apr 02, 2021 8:08 am

Yes

Geoff
S2 FHC Light Blue
S2 OTS LHD - RHD full restoration

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