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Bps

Member Since: 14 Feb 2016
Location: Lancashire
Posts: 822

Series 3 petrol carb vacuum issues

Just wonders if anyone can give me some pointers

Series 3 2/14 petrol, fitted with Webber carb.

When running the vacuum on the carb is enough to feel it sucking your finger to it. As soon as you connect the pipe to the dizzy it pulls the bob weights straightaway and runs too far advanced.

Without the vac advance connected it runs like a Swiss watch and timing is bang on.

Can I restrict the flow? Fit a regulator? Just not sure on the next steps, carb has been stripped, cleaned and rebuilt with new jets, seals, gaskets and float valve.

Any thoughts would be appreciated

Cheers brad

26th Mar 2024 7:56pm

BaronDefenders

Member Since: 28 Jun 2019
Location: London/Cotswolds
Posts: 895

2004 Defender 90 Td5 CSW Santorini Black

On my V8, there’s a small filter-looking canister in the vacuum line from the carbs to the distributor. It only allows higher levels of vacuum to bring on the advance. I don’t know if they were fitted to Series, but you could try one of those? Charlie

1949 Series 1 80 (SOLD)
2002 Td5 90 (SOLD)
2008 Freelander 2 (SOLD)

1958 Series 2 88 Pastel Green (2019 LR Legends Best Restored)
1983 V8 110 Limestone (Previously owned by Tom Sheppard MBE)
2004 Td5 90 Santorini Black (Td5INSIDE Powered & Rebuilt by CSK)
2012 Puma 110 Zermatt Silver (Overlanding Build)

Instagram: @BaronDefenders

27th Mar 2024 7:41am

Bps

Member Since: 14 Feb 2016
Location: Lancashire
Posts: 822

Thanks for the info. I’ll have a search and see what I can find.

27th Mar 2024 9:59am

TexasRover

Member Since: 24 Nov 2022
Location: Paris
Posts: 1002

2002 Defender 110 Td5 DCPU Chawton White

The Weber is not the standard carb for the 2 1/4. Standard is the Zenith and it runs really nice with the Zenith if you know how the refurb them right. The Weber was sold as an upgrade, but I found it's not running right. Both are crude things compared to a proper Stromberg variable jet type, which would be tricky to retrofit.

Normally you would use a ported vacuum for ignition advance which blocks the timing advance vacuum port at idle, assuming you have adjusted your idle circuit right and it's not running on the butterfly with too much idle screwed in.

I am not sure about the Weber has a ported vacuum but I would research that first. Unless some sort of valve/reservoir is part of the normal Weber setup I don't think just adding bits would make it work right.

Personally I would hunt down a good used original Zenith and properly rebuild that. Ideally you get two and dial them both in then leave one on shelf for spare. The biggest problem with the Zenith is a leak in the idle emulsion channel which makes the engine stall. You need to lap it and use a small amount of RTV on the mating surface with a quality gasket.

27th Mar 2024 10:16am

Bps

Member Since: 14 Feb 2016
Location: Lancashire
Posts: 822

Thanks for the info. unfortunately the original carb is long gone. I’ll check the idle. I did try a copy zenith but it was rubbish, ran great for 2 days then went off the boil.

27th Mar 2024 2:23pm

Bps

Member Since: 14 Feb 2016
Location: Lancashire
Posts: 822

Having studied the zenith and the Weber the vac feed on the Webber is below the butterfly rather than above on the zenith so the vacuum is to great on the Webber.

3rd Apr 2024 2:37pm

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