Need some help adjusting those annoying lil twin solex\'s!

Hey guys... i've got another silly problem i can't work out...

2ltr engine... twin solex's... i think they are running rich so i tried adjusting them using the online guides at http://www.type2.com/library/fuel/dualsol.htm and http://www.ratwell.com/technical/DualCarbs.html

It seemed to be running ok but its idling very very slow and the idle adjustment screw is in as far as it goes... Also when i idle at the lights for a while, then go to move off, the accelerator is sluggish and ive been stalling.

Any suggestions as to whats gone wrong before i take it to someone who is more vw wise than I ? 🙂

(and if no suggestions... then any recommendations as to melbourne vw people who are good with carbies)


Thanks again guys 🙂

Hi

This is an article I wrote on the subject.

Tuning tips for tips twin carb Kombis

The twin carburettors on 1700, 1800 & 2000 Kombis can cause no end of problems unless they are set up correctly. I will try to explain how to set them up in plain English. First, you must understand that there are actually 3 idle systems on these carburettors and they must equally contribute to the idle speed and mixture for smooth idling and acceleration. I will first explain the 3 idle systems. The right hand carburettor has a sunken mixture screw that was originally covered by a protective plastic cap. VW did not want you to touch these settings but if the plastic caps are missing, every man and his dog probably has had a twiddle with them. Idle speed or throttle opening at idle is controlled by a small screw on the linkage lever. The left hand carburettor contains the same system with the addition of the 3"' idle circuit. This idle circuit has two adjustment screws on top the large one for idle and the smaller one for mixture adjustment and that funny little black steel pipe on the left hand side air cleaner supplies air to the 3rd idle circuit and fuel is supplied from the left hand side carbie float bowl.

The purpose of this exercise is to get all systems contributing equally to the idle mixture. To set the idle speed and mixture you must first disable the 3rd idle circuit. You can do this by removing the wire from the large solenoid screwed into the carburettor top the revs should drop to about 500 rpm if the system is working correctly, which it probably isn't. The large solenoid in the left carbie top often comes loose and enlarges the hole it screws into. If this is the case, it can be helicoiled. You will usually need a new solenoid as the cotton reel shaped plunger on the end will often be worn and will not seal, and the mating surface the for cotton reel to is often damaged. If this is the case you can usually do away with the solenoid by just plugging up the hole with a bolt or some thing and a little bit of araldite to seal it

The 3rd idle circuit can also be disabled with help of an assistant. Remove the black steel pipe from the top of the left hand carbie together with rubber elbow and ask your assistant to put a finger over the brass tube that pokes out of the left hand carbie top.

The solenoid is supposed to stop run on, but if the other 2 idle jet solenoids on the left and right carbs are working and the compression is not too high to cause run on or the idle speed is not to high, it should not cause any problems.

After having disabled the 3rd idling system (also called the central idle circuit) you can start adjusting the idle mixture and synchronise the left and right carbs. It's important to have idle set low on this conventional type idle system (about 500-600 rpm) otherwise when the central idle is brought back in the idle will be too high and the large idle screw will have no effect. Disconnect the linkage from carbie levers, give each carb, blip and check idle synchronisation. You can do this three ways.

With synchronisation tool (pea in a tube) or by removing the power wire idle solenoid, one at a time, and noting the difference in idle speed on a dwell tacho or by ear, or by removing no. 2 and no.4 spark plug wires one at a time and noting difference in idle speed side to side. The first two methods are the least exciting, the third method can give you jolt via the high tension lead, also after any adjustment on the small idle screw on the linkage lever, blip the throttle and re-check your idle speed difference. Now comes the mixture adjustment. You either need an exhaust gas analyser or a pretty good ear to pick up where the motor idles the best with the individual mixture screws wound in as far as possible and still having a smooth idle. It's best to alternate between he mixture adjustment and the idle speed differences a few times as they both have bearing on one another and still keeping the idle speed about 500-600 rpm. Also remember to give your assistant a chance to change fingers occasionally or you could plug one of the rubber elbows to do the same job.

After you have this system running sweetly, you can get back to central idle circuit. Reengage by re-connecting the wire to large solenoid on left hand carb and blipping, throttle or by extracting the assistants digit. Then just set the central idle circuit mixture and idle speed back to around 900 rpm.

Before beginning this procedure you should also check that the motor is correctly tuned, eg timing point gap and valve clearance.

Steve

cool.... thanks so much... i'll go give it a try 🙂

Hi Steve,
Great article.
Can I put it up at the aussiekombicampers.com website?

tia

ergh... i cant get it right... i think im carburetorilly challenged.

The idle mixture screw, and idle adjustment screw are both in all the way... seems they've been that way since before i touched anything. So i can kinda adjust the normal mixture screws, but it still seems to be running far too rich and it fluffs about when i give it a blip...

Hi Fekkin - or is it Ell? ;-)
Just a thought...is your balance tube connected properly at both carbs? I had similar symptoms in my 2L kombi when the flexible hose that connects to the RH carb had split.
I am not happy with my setup either so I'll be watching this thread. Hope you get it sorted!
Toby :thumb

man, had a richness prob with my carbs. Check your fuel bowl level and possibly jets. Remember there cars are 30 yrs old... it is likely a home handy man has had a go at the jets with a jet file or drill bit in an attempt to give the engine more fuel = *"more power"* but it doesnt!

check your jets and fuel bowl. Better still rekit them and start fresh :-)

modulus wrote:Hi Steve,
Great article.
Can I put it up at the aussiekombicampers.com website?

tia

Hi

No worries, just mention its from www.clubvw.org.au

Steve

i've given up... im gonna take it to the dub doctor!

thanks for the help though guys 🙂

fekkinell wrote:i've given up... im gonna take it to the dub doctor!

Yeah, that's what I figured re: twin carbies. Spend your time doing something you really want to be doing, like actually driving maybe.:P I gotta do oil and valves soon though, at least that stuff's easy hey?