Carbs

[Pummer67]

Hi all. I need to either replace or repair my twin solex carbs on my 2l air cooled. It is running really lean at present and won't adjust at all. I have been told the new webber ones are a nightmare to set up so I don't know what's best to do. What's everyone's thought?

Mark

[Pummer67]

Just realised I put this in wrong area. Could a admin move for me? Or should I start a new topic in tight area ?

[itchyfeet]

Or should I start a new topic in tight area ?

We don't have an area for tight people

for future reference you can delete a post you make until somebody replies....oh too late

[Pummer67]

We might not like tight people but we don't mind a tight hole

[Pummer67]

So can admin move it or should I just start a new one

[mr_nunn]

You can get them refurbished e.g. Gasure in Chester, or postal services e.g. gower and lee. They will sort out air leaks especially at the throttle spindle which often cause problems. I did this and was happy with the outcome.

Sent from my GT-I9505 using Tapatalk

[Pummer67]

Thank you.

Is there anyone a bit more local to Bournemouth?

I think I would like to just pay someone to rebuild them and tube them up properly.

[multisi]

I have a set of carbs, low miles. For sale. pm me if you want.

[burnzdog]

Ive just put some twin ICT 34s on my 2L CU. Eurocarb pre-jetted for the engine but its running rich. ALso is you use the EMPI linkage its not great.

[Pummer67]

Ive just put some twin ICT 34s on my 2L CU. Eurocarb pre-jetted for the engine but its running rich. ALso is you use the EMPI linkage its not great.

Ok. So I think sticking with originals is the best option.

[sarran1955]

Hello,

Question: How lean is lean..give us some figures please..

Lean running comes from air leaks into the system..typically between carb and inlet manifold, or between inlet and cylinder head.

Usually due to tired gaskets ....or silicone goop..

On the carbs them selves there is not much to go wrong.....tampering apart..

Check the solenoid valves(little cans with an electric lead) are screwed in tight, and that there is not any screw holes in the main carb bodies that do not have a screw or bolt in..

This gives you an idea of what we are trying to do:

https://www.youtube.com/watch?v=4qayyc9Z4E0" onclick="window.open(this.href);return false;

then:

https://www.youtube.com/watch?v=dsfo5ATgBp0" onclick="window.open(this.href);return false;

Hope this helps,

Cordialement,

[djaychela]

I've recently bought a 2L Air Cooled T25 (CU engine), and when I originally got it I thought the carbs would need replacing - it ran like crap - pops and bangs all over the place, no power, flat spot a mile wide, etc.

Part of the problem was the ignition system - it had been much messed about with, with the standard setup replaced with a non-vacuum advance dizzy, and then badly set up to boot. Replacing the stock setup and getting that working properly (with sage advice from BigHerb on here) changed things a lot.

Then, setting the carbs up properly and curing any leaks took it to where it probably should be - the difference in it now that things are set properly (throttle gap, choke amount, throttle linkage, etc) is worlds apart. It starts as it should do, runs as it should do (it's never going to be a fire-breather!), and that's good enough. I'd think that if you go through everything and sort them one step at a time, it'll be OK. FTR, I'm in Bournemouth, but I don't do this kind of thing for a living, it's just a hobby.

What have you been doing to try to change the mixture? There's no adjustment (that I know of!!) for the main mixture, just the idle mix setting?

Also, are you actually measuring the mix with an exhaust gas analyser? Many's been the time when I've thought something was rich/lean to be shown to be wrong...

Anyway, is everything stock as it should be? Is the DVDA dizzy working as it should be? My carbs had been so messed about with that it wouldn't work properly initially as some chump had adjusted the throttle stop to try to compensate for all the other mistakes made elsewhere - and oddly, doing it by the book (have you read the ratwell page on their setup - very similar to in a T25) did the trick; it's almost as if VW had an idea what they were doing... almost!

[Pummer67]

Hello,

Question: How lean is lean..give us some figures please..

Lean running comes from air leaks into the system..typically between carb and inlet manifold, or between inlet and cylinder head.

Usually due to tired gaskets ....or silicone goop..

On the carbs them selves there is not much to go wrong.....tampering apart..

Check the solenoid valves(little cans with an electric lead) are screwed in tight, and that there is not any screw holes in the main carb bodies that do not have a screw or bolt in..

This gives you an idea of what we are trying to do:

https://www.youtube.com/watch?v=4qayyc9Z4E0" onclick="window.open(this.href);return false;

then:

https://www.youtube.com/watch?v=dsfo5ATgBp0" onclick="window.open(this.href);return false;

Hope this helps,

Cordialement,

Hi thanks for advice. I think the reading was just above 0.10. I can't remember all the other readings on the computer. Just the one at the top left of the analyser. My cousin altered a tapered screw which I think he said was supposed to be only about 2 and a half turns out but this was way more than that. He said the further out it went the more fuel it lets in and with this wound right out it didn't alter the reading at all. Could someone take a photo of the small vacuum pipes that come off the dizzy and two to air box. I have one that isn't connected and I can't for the life of me work out where it's supposed to go.i will check all your suggestions. My mate said there is something that wears inside the carb which allows more air in but I can't remember what this was.

Mark

[Pummer67]

I've recently bought a 2L Air Cooled T25 (CU engine), and when I originally got it I thought the carbs would need replacing - it ran like crap - pops and bangs all over the place, no power, flat spot a mile wide, etc.

Part of the problem was the ignition system - it had been much messed about with, with the standard setup replaced with a non-vacuum advance dizzy, and then badly set up to boot. Replacing the stock setup and getting that working properly (with sage advice from BigHerb on here) changed things a lot.

Then, setting the carbs up properly and curing any leaks took it to where it probably should be - the difference in it now that things are set properly (throttle gap, choke amount, throttle linkage, etc) is worlds apart. It starts as it should do, runs as it should do (it's never going to be a fire-breather!), and that's good enough. I'd think that if you go through everything and sort them one step at a time, it'll be OK. FTR, I'm in Bournemouth, but I don't do this kind of thing for a living, it's just a hobby.

What have you been doing to try to change the mixture? There's no adjustment (that I know of!!) for the main mixture, just the idle mix setting?

Also, are you actually measuring the mix with an exhaust gas analyser? Many's been the time when I've thought something was rich/lean to be shown to be wrong...

Anyway, is everything stock as it should be? Is the DVDA dizzy working as it should be? My carbs had been so messed about with that it wouldn't work properly initially as some chump had adjusted the throttle stop to try to compensate for all the other mistakes made elsewhere - and oddly, doing it by the book (have you read the ratwell page on their setup - very similar to in a T25) did the trick; it's almost as if VW had an idea what they were doing... almost!

Hello mate. I presume that's what he was altering was the idle screw then. I'm no mechanic just trying to learn things as I go along. I have a basic understanding of engines. We measured on a gas analyser and the reading was around 0.10. When the engine is hot it won't start which I presume is because the fuel is evaporating before it sparks and I am overheating on journeys of over an hour. I'm going to wareham for the weekend in a bit so see how it goes. It has always been the same since I bought it so I'm hoping it maybe a bit better at going up hills once I get to the bottom of this. I think I need to make sure there is no air leaks before I start doing anything to carbs then.

[djaychela]

Hi Mark

It sounds like they need resetting from scratch, and any other issues sorted - as I say, mine was 'orrible when I bought it, and now it's pretty good.

I wouldn't necessarily assume evaporation for the non-starting when hot - I think that it's making assumptions that often leads down blind alleys. If the idle mixture screw isn't making any difference, then there's probably a reason for that, and it's finding what it is, but getting a baseline (i.e. everything set as it should be, and the ignition setup correct and timed up properly) is important. There are plenty of places for air leaks on these engines, and one will definitely ruin the party!

It is, of course, possible that the carbs are worn out (and throttle spindle wear leading to an air leak is certainly a possibility), but before spending £££ (and having some downsides) I think it's worth a bash, particularly as there's no significant cost of getting everything set up properly, other than time.

This page is worth a read: http://itinerant-air-cooled.com/viewtopic.php?t=7767" onclick="window.open(this.href);return false;

On the vacuum pipes front, there is one off the vacuum RETARD which goes to the link pipe for the idle circuit - this provides vacuum at idle, allowing the ignition to be retarded (to about 5 degrees ATDC, IIRC). This is also connected via a T-piece to the airbox temp sensor (and obviously the retard part of the dizzy diaphragm). The other part is the advance, which is connected to the left-hand carb, and provides a vacuum signal at all times -except- at idle. If the throttle stop screw has been messed with then this may provide vacuum all the time, and stop the retard section working. The second connection on the airbox connects to the flap on the inlet which selects hot or cold air.

Have a look here:

http://s106.photobucket.com/user/phade1 ... n.jpg.html" onclick="window.open(this.href);return false;

1 - Dual Vacuum distributor (one connection for advance, one for retard - in pic, left-hand connection is retard, right is advance).
2 - t piece, connected to dizzy, airbox temp sensor and link pipe in idle circuit (vacuum at idle)
3 - connection to LH carb (vacuum at all times except idle)
4 - connection to selector flap from airbox.

On mine, where the carbs were set up wrong (screws all fiddled with), the dizzy wasn't getting a vacuum signal at idle, and it turned out basically every setting had been messed with, so I took them off, did some research, cleaned them up and reset everything to factory. Took me about 2 hours, start to finish, and it was a world apart. The problem is (I think) that most mechanics now don't have to do stuff like this, so they just go "ah, Solex *$^%, put a Weber on it, it's knackered" and that's that.

Anyway, enjoy Wareham, hope it all works out. I can take a look at some point if you want? Problem is I'm not around until end of next week...

Darren

* E D I T to remove incorrect information in case someone else gets stuck!