My fronts are 20 year old Michelins, still soft and in A1 condition, proper rubber!

Those last two words say it all....

Nothing I have come across in our "modern" world has the same density, wearability, flexibility etc. The words "fit for purpose" come to mind. Just replaced two Hancook tyres at great cost after a mere 12,000 miles on previous two. Never again. 

Too true Paul can think of buggy folks in the 70's on dunlops lasting 50k miles and not perishing our sp sports 7/2021 are cracking already at 2 years and 3 months old may go cheap next time these were £650 for 4 with multi buy discount

Carburation......

Just thought I would share the experience of the last 18 months as I trawled through Type 1 air cooled engine  carburation as fitted to my buggy.
Am just about to fit twin Weber ICT34`s and will deal with that last once fitted....

As an opener for those who may be less than familiar with carburation ....  In order to set up you single or twin carb set up the engine must be in first class order to get best results. A worn engine with a worn carb will run and go on doing so for years but if you spend time and money on building / rebuilding your buggy go the extra mile or two and have an engine that runs well in all conditions and returns the best mpg that you can get. (Don`t expect mpg like a modern of early fuel injected engine).

To start with..... the engine should have good compression on all cylinders. Equally important the pressure should be very close to each other.  Type 1 engines have variation on the factory compressions depending on year / emissions control etc so the ball park is
"Wear Limit"...  100psi  ie if this low the engine is very poorly.  Again VW have variation in percentage difference between cylinder pressure acceptability. So use 10% variation between cylinders as a max. My engine, which was fully rebuilt, shows 140/5psi @cylinders. Don`t be concerned if you find say 124/130 psi.(Do each cylinder 3 x and take average). Do with engine cold. Ignore any advice that says do with throttle fully open it`s not a racing engine.

In addition the tappets need to be set correctly. Also double check that the timing of distributor in relation to No1 cylinder is accurate. Use any guidance to achieve distributor timing that you feel comfortable with. A distributor with mechanical vacuum advance is better than one without due to it`s better ability to adjust advance/retard. (The vacuum unit needs to be in good condition).

OK... you have an engine that is mechanically sound. The tappets are set and the timing is accurate....
Take a look at the photo.. (This is not my sketching. Is in public domain so copyright not applicable  )

Note the shape of the main body. It tapers twice.  Entrance for air at top larger dia than exit lower down which allows higher speed exiting the carb. (This sketch does not have a choke butterfly shown nor the float needle valve).  The sketch depicts the simple principle of carburation nothing more.



(More to follow starting with 34PICT3 which is, in my opinion, German engineering design at it`s best).

Right I`m back.... yep the proverbial bad penny....

Just to back track a sec..... Want to change a phrase to ensure no confusion for any one new to old time carburation.... I used the term "fast idle" earlier... Can I change this to "mixture" as this term is probably more common.... 
(Idle mixture set by "mixture screw". Open throttle - mixture set by float only)....

So ... The Solex 34PICT3.... I have always wondered what it is that makes most people shy away genning up on late type carburation just as they do with electrics. Carburation and electrics are a real buddies in this respect. Carburation... mixing petrol and air to go into the intake manifold/s. 1 fuel route, 2 or 3 fuel routes plus spray bar/s and drillings. All really simple.... Electrics... You need 12 volts to a light bulb, a wiper motor and so on. 2 routes  -  negative wire, often via grounding at body chassis or. Positive wire to bulb/wiper motor etc. (sometimes via a switch or a fuse box or a relay and so on). So many times thro` the decades I have sat down with someone with a Haynes manual and tried to explain the simplicity of basic car wiring. They take one look at the multicoloured tracks on the page/s and just have a mental block. Same with things like the 34PICT3 etc.  Screws, jets, drillings, 1 spray bar/2 spray bars and basically speaking 3 fuel routes. Yes it has other considerations but the 3 basic routes are all you need to understand in order to set this type of carb up and know what each turn of a screw does.

Firstly take a look at the photo.... Concentrate on the dots which appear in three colours.....




The blue dots represent the flow of air from atmosphere.

The red dots represent fuel flow  (Note the red dots appear to be 3 separate "bits" but they are 1 route as the drillings are omitted for clarity).

The pink dots are the petrol/air mix that pass by the throttle body to the intake manifold.

That is the "3 fuel route system".

On the left hand side I have labelled the emulsion tube, (You will find this after removing the top section of the carburettor next to the float. It can lie under a hex bodied jet open to atmosphere or it can be a one piece tubular structure. (You cannot mistake it as it is a tube with round perforations in it). On the left hand side I have labelled the throttle butterfly. Note this sketch shows the butterfly in a slightly open position so that the little drillings for fuel to enter the "venturi body" are shown. (I will come back to this a little later).

On the right hand side I have labelled the "solenoid cut off valve". This was added at some point to cut off the fuel when the ignition was switched off to prevent engine "run on" something I have never seen occur in this country. Above this is the air/petrol "mixture screw". Above this is the "air bypass screw". This is the screw that you use to adjust idle speed.

These two screws are all that you need to adjust once the throttle butterfly fractional opening is set.

These carbs came with the mixture screw preset "at factory". The opening was plugged off and the intent was that this screw did not need any further re-adjustment. It is many years ago since I came across a carb with the plug still in place you can be certain any carb you come across has had this screw fiddled with and many times at that.

That`s a basic description then. Another photo to follow showing an actual carb and details of how to go about setting it up. In addition an explanation based on a personal experience as to why a 50 year old 34PICT3 can be perfectly usable...

the 3 pict 3 was the last of the carbs trying to meet ever lower emissions limits, the adjustment is out for leaner and in for richer mixture which is reverse to all previous carbs the had a idle mixture screw they also suffer from having a plastic/nylon bushing for the butterfly spindle which wore rapidly and allowed air in.
You can no longer buy adaptors to fit 34pict carbs to the smaller inlets but you can still get ones to fit 30/31 carbs on to the larger manifolds which hints at troubles, emissions are not an MOT problem these days as historic goes on excessive visible smoke for failing.
If you have a 34 working well keep it but if it plays up a earlier carb is fine and easier to set up.

34PICT3......  Photo is of the carb that came with the beetle..... i wanted to have this carb pro` rebuilt in case I had any issue with providing proof the carb was original to the engine and the engine original to the chassis. (The carb still had it`s serial no tag). I didn`t give a thought to this when I obtained the donor which originated from Uitenage in South Africa. VW could not provide a birth certificate for any classic VW from South Africa, My age and school day history lessons thro the 50`s and 60`s should have clicked regarding this but it didn`t. Details from a VW club of any kind was not acceptable back in 2016 but things have changed. A "recognised club" providing confirmation of chassis/engine age is now technically accepted. Birth certificate application has also changed. It`s no longer done thro` the original VW museum in Wolfsburg. This certification is done thro the department that took on the sales of original VW classic spare parts.

Anyway it`s always one step forward and two back in a from scratch build. The carb was, I am sure original, being Kafer manufacture and the serial number tying in with the engine/chassis year.

Manx David enters this story at this point. I wanted another 34 carb so that I could remove the one I had and send it off for a rebuild. Dave kindly let me have the carb free of charge as it had laid around for ages and butterflies etc were siezed. Upon approaching Gower & Lee they told me that they would not rebuild any carb that was not of original manufacture including kafer variant. So off went the carb that Dave gave me as it was a genuine german solex. (I kept this until very recently). (A pro rebuild of a carb is not cheap as you may expect but the "repair kits" available from the usual sources have basic parts only. (That`s not to say they are not helpful).

Now then.... the kafer..... Enter another forum member.... See what an asset this forum is    .....  The carb had stood idle for possibly years. Fuel had dried out leaving crusty remains and I knew the drillings/one way valve would be seized. Buggy Pete advised separating top from bottom. Heat hot water to simmering and simmer the two carb halves in the water for an hour. Waited until the wife was out  . Borrowed a pan and kept the water simmering for an hour. This cleaned everything out and freed off the two balls that make up the one way valve. Put a bit of fuel in and petrol came out of hoop etc just as it should. Carb ran faultlessly.

Here is where I explain why a I am impressed with the kafer 34.  50 years old nearly.... all original parts except for maybe o rings a gasket... Mid year 2022 took the buggy for exhaust emissions and return to idle checks at my local garage. Motor bike silencers on buggy so each side was checked for emissions , (co2 & hydrocarbons). I, and the tester were staggered.... The results were far below the max allowance for a 1975 engine.  Below are two photo`s of this carb and I will go on to describe how to set it up and I cannot see why anyone should have trouble with them despite the age as long as the engine is set up first and tha carb is not totally past it and some are.

Note the auto choke markings on the 34 photo that I have highlighted in red. Also the etched line in the heating element housing. reproduction 34`s don`t all have them. There was a forum member who "lol`d" me when I first mentioned the summer/winter settings but this what VW identified these markings as way back in time. This was just a "ball park" thing for setting up/replacing the heating element body. The centre marking was the re-assembly fitting point. The top line was a ball park "summer" setting and the lower the ball park "winter" setting. Very few people back then ever bothered with altering choke butterfly position if the engine appeared happy.

So your engine is sound with all settings as they should be. If you have a distributor with vacuum advance you have checked it works by sucking on the pipe and watching the plate in the distributor move.

Looking at the photo note the point I have marked "throttle butterfly screw". This screw, unlike earlier carbs, is not for setting engine idle. In the photo prior, where it shows the three fuel routes, note the small drillings local to the throttle butterfly flap.... (The 34 carb has many variations.. you may have 1 tiny hole, you may have three). These are part of the 34`s fuel flow at start up to assist with starting/emissions. Just be aware they are there, the theory doesn`t affect your ability to tune the carb. The throttle butterfly flap should be fractionally open prior to start. So... connect the autochoke to a 12v supply, (earth thro carb body). Allow choke butterfly to open fully.  (Flap vertical). At this point the screw on the arm should point to the cam just below the very bottom step. Adjust the screw so that a feeler gauge gives you the gap. From this point do not adjust this screw at all. The throttle butterfly at start up will be where it needs to be for ever.  The official gap figure is  0.004 thousands of an inch which I think was 0.010mm. (I will check I have the metric figure correct)

Next have a can of "easy start" or "wd40" handy.  Start engine and spray from the can at carb base, at manifold joint rubbers and at manifold to head joints. Just a quick short squirt. If you have a vacuum leak, (air ingress), the engine will speed up briefly. Take care not to squirt any very close to carb air filter or this will cause the engine to speed up an may mislead you in checks.

All fine.... remove air filter and run engine to fully warm. Watch that the choke butterfly opens fully, ie vertical in carb carb throat.
(You have already proved that the solenoid cut off valve has opened otherwise the engine would not have started).
(Make sure that you are working such that you are not breathing in the exhaust fumes. The modern E5 unleaded is very noxious).

With the engine hot and the air filter re-fitted you are ready. Look at the photo again. There are two adjusting screws. The larger one is the "air bypass screw". The smaller one is the "mixture screw". Take care with long bodied screwdrivers if you choose to use them. It is possible to short the solenoid 12v connection if it is exposed. The air bypass screw adjusts the idle speed. The mixture screw richens/weakens the fuel/air mix.

If you have a tacho you are looking for a idle speed of 850 to 900 rpm with the engine hot and choke flap fully open. If you don`t have a tacho then a energetic idle speed is the ball park.  Bypass and mixture screws. Both have "o" rings. These need to be in good condition as does the mixture needle screw. IMPORTANT.... take care when screwing in the mixture needle screw. Gently goes it is the shout. With the engine off turn both screws gently clockwise until they "bottom". Turn both screws anti - clockwise 2 turns and then just a fraction more. With this ball park setting the engine will start and run. We are now aiming for a idle speed of around the 850 mark but more importantly the point where engine runs smoothly. We achieve this by firstly  adjusting the air bypass screw. (usually anti clock wise is needed but in or out until the engine has a speed appears close to what you are looking for. Next the mixture screw... This screw adjuster is very precise so the difference between an over rich and under rich mixture is a small fraction of a turn. Initially however turn it in or out until to get a smooth idle. Go back to the bypass screw and turn until you are close to the 850/900 rpm. Go back to mixture screw then back to bypass screw. This sounds over the top but the more attention here the more chance you have of getting it right. When you are happy with the low speed idle open and close the throttle quickly. The engine should speed up evenly and fall back to a steady idle quickly. If this hasn`t worked for you and you have issues when driving the vehicle through the gears and on to fast running you may have another issue. Will cover that later.

VITAL......  The last 15 months running my buggy "in anger" has simply further strengthened a fact that I already knew. If you run a single carb on a Type 1 engine, single or twin port, you must ensure the "heat riser pipe" is in place and operates at it`s full designed temp` and that is very, very hot. Without this, when the ambient temp drops to approx 14 degrees C, the petrol air mix falls out of suspension as soon as it leaves the carb. The carb and inlet manifold flange area "ice up". The more the icing develops the more erratic the engine becomes until it stops....  Each and every inlet manifold I have got from scrap yards to more recently from ebay are offered saying "heat riser clear". This proves to be nonsense. Yes you might get a trickle of water thro but that`s as good as useless. Years of use causes carbon build up gradually reducing the bore thro the pipe which reduces the available heat to the manifold/carb. The carbon deposits are a good insulator. Not what you want. It is very easy to fully clear a riser pipe no matter how blocked. The best method I have developed is to use the specialised "Bowden Cable" that is supplied for use with the Lucas wiper motor system. The has the twisted strand structure but in addition a spiral wrap wire running axially along the strand bunch. (This to driver the wiper arm cog). The spiral keeps the strand bunch tightly together but the structure remains very flexible. All you need is a drill with a variable speed. Cut a length of cable. Remove about an inch of the spiral from one end and splay out the strands. Fit the other end to the drill and on a very slow speed, and with care not to allow the drill to speed up and whip itself around the drill and bend, use the splayed end to scour out the carbon deposits. Be patient. Persevere. It will take about an hour but at the end the riser pipe will be as clear as when it came out the factory. You know you have done a "proper job" when the pile of crap is several inches high.

Another factor that does, beyond any doub,t improve the heating of the pipe is the two riser to exhaust gaskets. VW designed them, one with the standard size central hole and the other much smaller being 6mm in diameter. VW manuals of the day stated this differing of diameters caused a difference in "pressure" from one side of the pipe to the other which encouraged hot gas flow thro` the riser pipe. I no longer remember for certain which side  exhaust/riser connection VW stated the smaller holed gasket should go but they did. However I cannot detect any difference wether it goes on the nearside or offside.

Beware...... the aftermarket manifold with heat riser pipe is a very poor imitation. The "aluminium" solid section around the manifold is far too short. Not enough material to aid heat transfer from the riser pipe to the manifold.

IMU - 12v heater "blanket"...... I have one fitted. I have no heat riser pipe. (The worst omission of the whole of my buggy build ).
This heats up drawing approx 4 amps but is too small to have any real effect in the winter months.

You are at the point where you know your engine cylinder compressions are sound. Valve clearance all correct. Ignition timing correct and if vacuum advance fitted it works. No vacuum leaks, (air ingress). Do you need to be sure of anything else ?

Yes....  Float level as it should be. Yes... great.

One more thing.... There is no such thing as a carburretor that is prone to over fueling/flooding. (I was very surprised when I took a look at various forum threads regarding Weber ICT34`s when this cropped up quite frequently. 

Here is what happens to a carb subject to a "too high fuel" pressure... Carb/carbs in good condition..... Engine rpm up and down in normal driving.... Over pressure forces float down... excess fuel enter float chamber.... needle of needle valve up and down like a yo yo and  wears it at the point where the needle end touches the float/float arm. Over time the car ends up running like crap no matter how you take care in the basic tuning.

Electric fuel pump.... These use a metal rod and a coil, (solenoid), to operate as a fuel pump. The pump, when fitted as a stand alone device, will try to pump when engine is off up till ignition is off. Bad news for the carb. Higher than carb design fuel pressure present... with engine off carb needle valve open.... fuel down carb throat... I have seen this result in fuel in the oil, very bad indeed....

Ok... I am turning into shakespear with this subject but bear with me because when a fuel/carburation system is in or near correct ball park the engine will run, idle steadily on choke, idle steadily when hot. Will restart correctly when has been shut down hot. Will accelerate smoothly. Will not bog down under full throttle etc. Note my words "bog down"... a good term and you will know if you have this situation. If you are suffering from this and no amount of carb adjustment of tweaking ignition setting then it is "over fuelling". Jet size/s wrong possibly but equally possible to be fuel over pressure if you have fitted an electric pump. (Hope I am showing a scenario where "everything" has to be in the right ballpark or you will end up tearing your hair out trying to solve what is causing your engine to run "unhappily).

If you are bored now then read no further..... If not then follow further and go and fit / twiddle with what you have..

Still with me.... read on...

34PICT3..... Setting float level....    VW made this real simple with this carb.... No bending of float hanger.






Photo.... Needle valve assembly.....  This one has an aftermarket fibre washer...  VW original used metal washer and they were obtainable in varying thickness.   (Just like shims).

Factory fit washer thickness....   0.5mm / 0.10 "       The 0.5,, took into account the gasket fitted between the top and bottom carb halves. Nowadays these gaskets come from paper thickness. (avoid), thro to near correct factory thickness. (Don`t over tighten top and bottom carb halves when re-assembling. Also check new gasket is correct and that all holes in gasket are correctly positioned and no carb drilling is partially/fully covered).

The measurement from the float chamber is ......  from fuel level in chamber to top face , (A to B in photo), should be 18mm.

Quick note about 34PICT3 made in China and definately made of chineseum...

Came across one of these at a cost new of approx 60 quid. Didn`t expect much from this but it was to be fitted temparily to another vehicle to keep it on the road.   Later fitted it to my buggy. Was very surprised by how well the engine ran. Cannot say how the last under long term use but if you are on a really tight budget consider this option.

I now come to another carb that I was given new and still in it`s box. The manufacturer was Brosal over the pond in Brazil. They state that there carb is of the better quality as opposed to Chinese version. I cannot pass a verdict on this.

The carb here is a Solex H30/31 PICT which I think must be a "hybrid" as I have never come across one by VW thro the decades....
Setting up is similar to what I have described for 34PICT3..

Throttle butterfly needs to be fractionally open. Same method as 34. Feeler gauge gap is 0.10mm.

Brosal recommend a warm engine idle speed of 650-700 rpm. I found this too low and kept my aim for the standard 850-900 rpm.

This carb needs an adaptor to allow carb to fit to the 1600 twinport manifold flange. See photo. This is simple to do but the overall height is about + 10mm approx` over the standard fitment of a 34 PICT carb on it`s manifold flange.

Usual use of air bypass and mixture screws for setting. Same process for float level check/adjustment. (Double check the float needle spacer dimension it varies across carb types).

The carb comes with 2 main jets. 150 factory fitted as supplied. A second smaller jet that I cannot recall the size of.. In my instance, and things vary across engine needs. installations etc, the 150 proved to large and no amount adjustment of the two screws would solve an over fuelling issue.  Really severe with choke in operation. (You may need to trial and error the other jets also but I was ok going with a smaller main jet.

Is there a decreased in power/performance....  Not to say there isn`t but I cannot detect a deficit as compared to 34 carb. So that`s it for the moment. Just waiting for other things taking up my time to ease off then I will see where I end up when I have the twin carbs fitted. (There are a couple of other tidy up jobs to do whilst engine is out).

Interesting what you say about overfueling on ICT34s.

I have an electric pump that only runs when the carb is asking for fuel, not the constant run type. For safety I have fitted a cut off switch and my routine is to stop outside the garage and turn the pump off while I open the door then drive in and engine on. Pump runs with the power breaker on so start up is power on and pump switch on, when it stops ticking ignition on and away we go.

When at a show once someone was interested in some led lights I had fitted so I switched the main breaker on for 10 minutes or so and I hadn't turned the pump off, it didn't appear to run as the carbs were full when I pulled up. But when I left the engine was flooded and took quite a bit of starting so I guess it just gave the odd tick I didn't notice.

Never had a problem in use, just if it's parked engine off power on

Hi Doon ,,  Carbs not over fuelling -   a theoretical statement.  Practice not always the same sods law proves.

I will be relying on you to keep me right on my ict install.

I took a look at the linkage that Eurocarb supplied..... At first glance the hex bar and rotating arms looked "over the top". Wasn`t until I looked closer and now I think I see why they are substantially built.  Luckily, looking closely, showed something that I may have over looked as I always clean up new threads with taps or dies. The carb/carb linkage threads are metric. The grub screw and hex bar threads for securing the arms are definately imperial. Guessing, but look to be 1/4 inch but what pitch I don`t know.... (Knew I was making a mistake when I gave all my imperial taps/dies to a good cause just before retiring  )

Paul,
I've still sets of unf/unc , ba and whitworth taps/dies if ever required.

Paul . Happy New Year👍

All my unf/imperial stuff is still in constant use on various old American golf buggies that I do odd jobs on. 

I never get rid of any tools ever!

Quote from: pepsi81 on January 10, 2024, 07:27:44 PM
Paul,
I've still sets of unf/unc , ba and whitworth taps/dies if ever required.

Paul . Happy New Year👍

Happy New Year to you..... Many thanks.... Some great people on this forum...