Carbs in bitz

[mac]

My "signature" pic - not such a simple carb as people think.



Just realised I've missed one part - the adjustable needle securing grub screw. (It's a spring loaded pin that screws into the side of the piston and bears upon the needle case to hold it in position whilst still allowing adjustment.

More (assembly) to follow - Mac

[mac]

New spindle, bushes and throttle disc fitted, linkage assembly begun.



Ready to fit new jet using Volvo special tool (press) and a caliper gauge.



Pressing in the jet.



Setting the jet height in the venturi bridge.



The choke assembly refurbished.



The choke assembly fitted and final linkage fitted.



New diaphragm and needle fitted to piston.



Piston fitted to body.



Ready to set float height.



Almost finished!



Now just calibrate and fit the temperature compensator - to be continued

Mac

[bogbasic]

Awesome work - its art, not science.

[volvomania]

Yep, the 'Mac' is back ...

[mac]

And now the finale -

The temperature compensator is probably the most mysterious and misunderstood component of a Z/S CDSE. It lurks under the white (but more probably dull amber) cover on one side of the main body and is part of the idle system.

The pic shows a dismantled unit and a complete one.
1. Is the main housing, 2. The bi-metallic strip, 3. The air valve plunger, 4. The strip securing screw and 5. The adjusting screw.



Broadly the unit sits in an air bypass channel with the plunger sealing the passage into the venturi - as the temperature rises the bi-metallic strip raises the plunger off its seat opening the passage progressively allowing air to pass "fine tuning" the idle mixture. The actual setting is a guarded secret and almost all publications (especially from Zenith Stromberg) advise leaving well alone!

However - the device frequently gums up and cannot be cleaned effectively without dismantling so -------------
Dismantle the device and ensure the plunger is clean and moves freely within the projecting nose of the main housing.
The bi-metallic strip should be absolutely flat - if not carefully straighten it. Engage the strip in the plunger and fit to the housing. Use a locking compound on the securing screw - ensuring the strip is centralised and the plunger moves freely up and down. Screw the adjustment screw in until the plunger just seals the housing nose.

Using a water bath and thermometer ensure the plunger just lifts off its seat at approximately 40-45C (if the valve is open at this temperature screw the adjustment screw in until the valve (plunger) just closes. Raise the water to 60C and ensure the valve is well open. Apply thread lock to the protruding threads of the adjusting screw on the underside of the main housing. (Yes, I know the Green Book suggests lift off at 20C but this seems to give a slightly weak idle mix)

The actual temperatures seem to vary depending on the vehicle and the source consulted but those given here seem to work well for the B19A.



Final pics of the completed carb.









The carb will now be fitted to a "local" 360 with carb issues to "prove the method" which will "release" a faulty unit for further investigation.
Oooooooooo convalescence can be fun!

Mac.

[trabitom99]

Awesome mac, amazing work!

Tom

[François]

Hi Mac,
I have seen the carburettors in real life at the Dutch VKB.
Currently I'm restoring my Solex CISAC 34-34 Z11 myself.
The base was warped and will be machined to make it flat again.
The float seems OK, but the main gasket has been demolished.
I guess this gasket is also used on a Citroen/Peugeot with 1.9L engines.
The previous pictures work well as a rebuild guide.
Hopefully the Solex CISAC series will follow soon, as I cannot find
a proper exploded view of this carb.

[volvomania]

Well, BBB sells the Z11 is available as a fully overhauled carb on it's website. You will have to hand in an overhaulable unit however.

[François]

Although I think Mac is doing a great job refurbishing all types of carbs for the Volvo 300, even the price you're asking sounds reasonable considering the amount of hours needed, I would like to do it myself. So the question is, where do I get the
bits and pieces to restore one, or, more to the point, does BBB sell a service kit for this carb, just as for the Weber?

[mac]

Hi there François - apologies for my delay in replying and thanks for your understanding of the work involved in producing rebuilt carbs!
I guess you are visitor on the BBB stand who was "sceptical" of my method for flattening the Z10/11 base castings - using a belt sander/linisher still works (so long as the belt platen is absolutely flat). "Real" machining is rarely needed I have found.
You probably realise I'm not a business, just an enthusiast trying to help keep 300s on the road and I calculate my costing to cover my expenses only - and most of the original work and prototyping/testing is self funded!

Generally, of all the carburettor types used on the 300 series the CISAC Z11 is the hardest to find parts for - whist the main unit is closely restated to the more familiar Z10 the upper casting is very different as is the choke pull off diaphragm and the float chamber vent valve arrangement. The main body gasket is specific to the Volvo version and can still be obtained (at a price) from Volvo Classic Parts in Sweden.
I've yet to find a supplier of a specific rebuild kit and at the moment it's a question of trying various kits to locate the parts needed. The problem is also that different suppliers seem to have very different ideas as to what are the correct items - it really is a bit of a minefield at present.
I fully understand your wish to carry out any work yourself but I can't really point you to one source. Given time I can almost certainly scrape together the parts you might need, and I know Robbert @ BBB is currently looking for a repeatable source of parts as well as I.

Information is also scarce since the Z11 seems specific to the Volvo (240/700 and 360) and about the only sources are Volvos own "green books" and service bulletins - both have diagrams and limited repair instructions (let me know if you can't find any info and I'll see what I can copy for you). My advice is when you dismantle your unit make copious notes and take lots of photos. Things are no more complicated than the Z10 but the float chamber vent is very different and very fragile - take care! (Replacements are still obtainable from Volvo Classic Parts but a price that makes it uneconomic (over 150€ last time I checked. Make sure the main castings are very clean (I use soda blasting and an ultrasonic chemical wash. Blow everything out with high pressure air and run a high evap solvent (like methylated spirits) through all the drillings and passages.
Always replace the float (it's a sponge composite and will over time absorb fuel) - actually you can reuse it but weight it "fresh from the petrol in the chamber" and only if less than 7g (any heavier means it has become porous). If you need a replacement float it's the same as any of the Solex CISAC Z series - genuine Solex unit are still about for 35€ or so.
(Try Webcon, Southern Carburettors, or Eurocarb in the UK) but I suspect there are several suppliers in France and Italy.

I'm sorry that there isn't an easy answer to parts and info at the present but do let me know if you think I can help you further.

Mac.

[François]

I managed to put the carb together, without any parts left. Mac, could you post some pictures about the basic adjustments?
How many revolutions from zero do I have to set the CO adjustment screw to get a reasonable idle?
Same for the idle screw, choke play, pneumatic choke adjustment, breather relief?
Currently the engine is idling well when cold and I need to pull the choke halfway.
However, when engine temperature is rising, I can completely pull back the choke and the engine is still idling at 1500rpm.
Trying to reduce idling by adjusting the idling screw, partially helps and when the screw is at its end, idling is still 1100rpm.
I took the car for a ride, but when asking some power (acceleration pump) the engine and drive line started shaking.
Do I have a mixture that is too rich, does the acceleration pump not function properly?

[mac]

Hi there François,

There are a number of basic adjustments that need to be set prior to tuning with the engine running.

Obviously the float height needs to be set - with the top gasket fitted.



With the choke fully 'on' manually operate the choke flap pull off mechanism and check that the flap opens by 2.5 - 3.0mm (the set value is 2.7mm)



With the choke fully 'off' set a gap of 1.0mm between the choke cam and throttle progression adjustment screw head.



The plastic nut at the base of the float chamber vent valve should be adjusted to give a clearance of 0.5mm (choke off).



INSTALLATION & ADJUSTMENT
SOLEX CISAC 34-34 Z11 1986 yr model on

Fit the thick insulation plate to the inlet manifold with new gaskets if necessary.

Secure the carburettor to the manifold with the nuts and washers. Tighten to 10 Nm (do not exceed this figure).

Fit the choke cable, throttle cable, vacuum hose, fuel line, float chamber ventilation hose, air filter trunking elbow 'O' ring, wiring to the idle solenoid valve and pre-heat thermistor.
Connect the air inlet elbow.

Start the engine (it will take a little time for the float chamber to fill) and run until hot.
Adjust the carburettor.


Adjustments should be made after the thermostat has opened but never when the thermo electric cooling fan is running.

Adjust the CO to 1.5% The adjustment screw is located in bore A. This adjustment should be carried out with the engine at normal running temperature.

Adjust the idle speed to 900 r/min.with screw B.





The above applies to the majority of Z11s but the 1985 year model 360 Z11 was fitted with a "constant CO" idle system and as such the CO% and idle speed are adjusted rather differently. If your carb has this system (identified by an extra, large, adjustment screw below the idle shut off solenoid) let me know and I will describe the procedure specific to that version.

Until you are sure your adjustments are correct it is not possible to say why you are "bogging" under acceleration but the symptoms are suggestive of a weak rather than rich mixture. A non functioning acc.pump is a possibility, as is incorrect float height or an air leak (which could account for the high idle speed that you cannot reduce.

Mac.

[François]

Hi Mac,

Thanks for your explanation. I indeed checked the float height with my Mitotoyu: 33.8mm
I'm in doubt about the 1mm gap between the choke cam and the top of the screw.
P.H. Olving manual says this gap should be 2.7mm as well as the pneumatic choke relief.
After many starting attempts, I ended up with an empty battery and completely soaked spark plugs.
I my opinion the CO mixture is far too rich. So I fully turned the CO screw to its limit (low CO).
The battery will be recharged overnight and I cleaned the spark plugs (Bosch WR7DC) with my USC.
New chances tomorrow! Oh, and the carburettor is a 1988 model, so no idle screw below the fuel cut off solenoid.

[bogbasic]

According to my blog, I also had too fast idling (about 2000 rpm) because "I had reassembled the outer parts of the carb incorrectly such that a plastic pivot in the throttle flap mechanism was not engaged in the choke cable mechanism." Probably not your problem, but you never know ;-

[François]

Today I purchased a new float for the carburettor from Robbert Jan.
I will exchange it next weekend and let you know about the progress.