Twin Weber Carb Issues

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peteinnit
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Twin Weber Carb Issues

Post by peteinnit »

Morning all,
I've been having a few carb related issues lately, (see this previous post http://forum.club8090.co.uk/viewtopic.php?f=37&t=165925" onclick="window.open(this.href);return false;), with the van being very hard to start when hot and then flooding and it's been getting steadily worse, it now happens on short trips as well. Cold start is fine. It was initially thought that maybe the fuel was getting hot whilst sitting in the carb. Whilst having clutch slave cylinder replaced I got my local specialist to have a look at the carbs, which are only 3 years old (Spanish one's not Chinese), and their opinion was that the float may be sticking, so the chamber is filling up whilst it's stopped and stationary (eg putting petrol in) and the throttle spindle is also warn. I spoke to Gower and Lee, who I bought the carbs from and apparently, spindle wear is quite common due to the pressure of the throttle linkage. So it seems I have 2 options, a rebuild kit, which apparently doesn't include a throttle spindle (assume this is the throttle shaft on the ICT34 diag), or get another couple of new carbs. The cost of both options will be similar, as the labour to do the rebuild will come out similar to the cost of getting new ones and having them set up.

It's very annoyng that these new carbs have only lasted 3 years (less if you include the period I've been having problems!). Has anyone else suffered similarly with new webers? Any advice opinions will be much appreciated. I will be asking the mech to try and make sure the throttle linkage is set properly to ease the pressure as much as possible this time as well. I live in Hastings, so also if anyone knows a local carb specialist that would be great.

Cheers,
Peter
T25 2.0l Aircooled CI - 1982

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sarran1955
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Re: Twin Weber Carb Issues

Post by sarran1955 »

Hello

A quote from the archives...



'Weber Carburetors - Float Level
FLOAT LEVEL - ICH, ICT & DICA
It is essential that the following directions be complied with in order to obtain correct leveling of the float.
Make sure (only for brass float) that the same does not show any pit. Check that the float can freely
slide on its axis.
Make sure that the needle valve is tightly screwed in its housing and that the pin ball of the dampening
device, incorporated in the needle, is not jammed.
Keep the carburetor cover in the vertical position, since the weight of the float could lower the pin ball
fitted on the needle.
Make sure that the float clip is perpendicular to the needle and does not have any indentation on the
contact surface which might affect the free movement of the needle itself.
With carburetor cover in the vertical position, and float clip in light contact with the pin ball on the
needle, the distance of the float from the upper surface of carburetor cover (with gasket fitted) must
measure 6.5mm for brass float, and 36mm for plastic float.
After leveling has been done check that the stroke of the brass float is 6.5mm, and the plastic float is
8.5mm. If necessary adjust the position of the lug.
Check that the return hook of the needle allows it free movement on its seat.
NOTE
: The operations of the leveling float must be carried out whenever it is necessary to replace float or
fuel inlet needle valve. In this last case it is advisable to also replace the sealing gasket, making sure that
the new needle valve is tightly screwed in its housing'

If the carbs have not been properly set up they will overfuel and be awful to start.

Sorry, but they are not what I would fit to a CU engine in a van.

Cordialement,

:ok
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Becky's Dad
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Re: Twin Weber Carb Issues

Post by Becky's Dad »

ICT's will run like crap if the fuel pressure is too high. It will also cause very rapid wear on your float valve

What fuel pump are you using ? you can buy electric pumps that output 2.1psi if your running the standard mechanical pump it could be putting out close to 5psi (my newly replaced one was)

Ideally ICT's should be run at a fuel pressure of 2 - 2.5 psi.

I'd recommend you change the float needle valves and fit a regulator (I run a Malpassi filter king regulator from Eurocarb)

I set my Webers up per Mike Leathers excellent write up and have no issues:
https://www.wayoutwestie.com/running-we ... ed-engine/
Last edited by Becky's Dad on 09 Nov 2018, 17:16, edited 1 time in total.
1982 Aircooled 2.0 Petrol - Autohomes Pop-Top

Becky's Dad
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Re: Twin Weber Carb Issues

Post by Becky's Dad »

......spindle wear is quite common due to the pressure of the throttle linkage

There should be no pressure on the throttle linkage ! - you have an additional option here, take it to someone that understands the carbs and can set them up and sort the linkage. Mike Leather if your near St Albans, Herts is locally renowned for ICT's on Aircooled motors

The linkages do vary in quality, I run a CB Performance linkage and filter set up andI'm pleased with the quality. The linkage hexbar sits between two fulcrum pins and operates the carbs via short adjustable rods. If the carbs were setup properly (ie with the linkage disconnected) there should be no pressure as the adjustable links are adjusted and connected in a no-load condition.
1982 Aircooled 2.0 Petrol - Autohomes Pop-Top

Becky's Dad
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Re: Twin Weber Carb Issues

Post by Becky's Dad »

One more thing after reading about your hot start issues -

What manifolds are you using ? there are some very short ones (Empi ?) that are prone to act like heatsinks and can give you 'misting' of the fuel in the carb barrel - its actually boiling the fuel. It could be if you have similar very short manifolds and you need an insulator/spacer beteween the manifold and carb.

Had a look at the Gower & Lee website and it doesnt list a kit or what manufacturer manifolds, linkage and filter setup your running. If your not 100% (or close to it) on playing with carbs I would recommend you check on what spec you have and email or call Mike Leather (wayoutwestie.com) as I feel sure he'll be able to help with a diagnosis - he knows these carbs and is an Aircooled guy - its all he works on. He's mobile too and travels.

wayoutwestiemike@gmail.com
07961 697500
1982 Aircooled 2.0 Petrol - Autohomes Pop-Top

peteinnit
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Re: Twin Weber Carb Issues

Post by peteinnit »

Thanks for all that info BD. I have a Pierberg electric fuel pump, just looked up the pressure range, it's 3.19-5.5psi! It's been on the van since I bought it in 2006! As for manifolds, again, this conversion was done before I bought it, so I've no idea which one's they are, I only bought new replacement carbs from Gower and Lee 3 years ago, not the whole conversion kit.

The hot start problem seems to be getting worse and happens even on short trips, so that maybe suggests that it's not the fuel overheating that's causing it. I think the wisest thing to do is take it to someone who knows them so will give Mike a call. I've also found Resto Classic's in St Leonard's on Sea/Hastings who specialise in old VW's and have half a dozen T25's sitting outside at any one time, so may give them a go as well. If the throttle spindle is worn on my carbs I think I will need to get new ones, as I don't think that is a serviceable part, or it doesn't come in the overhaul kits.

......

Just read the Mike Leather's link you sent me, it's brilliant, so many 'ah' and 'oh's as I read it! Think I will try the regulator and valve change as you suggest first and see if that improves things.

Thanks again
T25 2.0l Aircooled CI - 1982

peteinnit
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Location: Chingford, London

Re: Twin Weber Carb Issues

Post by peteinnit »

Just been looking at the Mapassi regulator you mentioned, is it a simple plug in to the fuel line between the pump and carbs? I'm guessing I'll need a gauge to measure the pressure as well. Thanks.
T25 2.0l Aircooled CI - 1982

Becky's Dad
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Re: Twin Weber Carb Issues

Post by Becky's Dad »

Sorry for the late reply .....

Yes, simply fit it after the pump and tee-out to carbs. you need 6mm fittings on the regulator. I used a cheap pressure gauge off ebay - but dont leave it fitted (some people do), they can fail and leak fuel into your engine compartment :shock:
1982 Aircooled 2.0 Petrol - Autohomes Pop-Top

peteinnit
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Posts: 90
Joined: 03 Jun 2013, 22:18
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Location: Chingford, London

Re: Twin Weber Carb Issues

Post by peteinnit »

Not really having the time and space I had the regulator and float needle valves fitted on Thursday, set at 2.5 psi and the hot start problem would seem to be solved! Went for a 400 mile trip along the M4 and M3, incorporating a few stops for fuel and sustenance and started 1st time every time with no problem. Drove fine along the motorway too, only slight annoyance is it's a bit 'kangerooey' and pops (a bit like when it's first started cold), when going slow around town, but assuming that is a fine tuning thing. On that point, has anyone ever used the Gunson Colortune spark plug thing? Someone mentioned it to me and was just wondering......

Thanks for all the advise, tis much appreciated.
T25 2.0l Aircooled CI - 1982

Becky's Dad
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Re: Twin Weber Carb Issues

Post by Becky's Dad »

My ICT's run really sweet even at low speed/rpm. The only issue I had was once the engine was warm it would 'miss' a beat intermittently which was annoying. Realised this was down to poor fuel choice (ethanol loaded supermarket stuff) using decent super unleaded it runs like a sewing machine, the Solex's weren't fussy on fuel but the Webers seem to be less tolerant.
1982 Aircooled 2.0 Petrol - Autohomes Pop-Top

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