Matra Enthusiasts Club UK
FAQ's: Frequently Asked Questions
- What carburettors were fitted to the Murena models?
The 1.6 had a Weber 36 DCNVA 16/100, whilst the 2.2 had a Solex 34 CICF 141 (TAL 13116.000).
These are both twin-venturi down-draught type units, with progressive opening. The earlier
Weber 36 DCNF on the Bagheera was a twin-venturi simultaneous opening type, but the later
36 DCNVA on the Murena 1.6 is a progressive. If you're not sure what that means, a simultaneous
opening carb. is like two carbs. in one and both throttles always open and close together;
whereas the progressive is like a single carb. at small throttle positions with only the
primary throttle opening, and a twin carb. above approximately two thirds throttle, when the
secondary throttle starts working. That makes the progressive more economical in general road
use. The Murena Prep 142 & 'S' models had two Solex twin-venturi side-draught units similar
to the well known Weber 40 DCOE type carbs. Some Prep 142 may have had the Solex C40 ADDAE,
whilst others and the 'S' had the later C40 ADDHE versions. As with all carburettors, the
specification numbers define the exact settings and you should always match these carefully if
you replace them. Even small changes can give widely different Venturi, Auxiliary, and Jet
settings, which may make the difference between the car running properly or not... and just an
incorrect float level can prevent the engine running properly!
To give you just one example, the 34 CICF listed above (TAL 13116.000) has the following specs.:
Auxiliaries: 4.0 Venturis: 25 primary 26 secondary.
Air correction jets: 190 primary 180 secondary Main jets:
127.5 primary 135 secondary... whilst a 34 CICF 161 (CIT 12572.000) sold supposedly as a
replacement (but actually for a CX2400) has the following specs.: Auxiliaries:
3.0 Venturis: 24 primary 27 secondary. Air correction jets:
180 primary 200 secondary Main jets: 130 primary 122.5 secondary. There are
other differences too, like emulsion tubes, but you can see from these figures that they are
not the same, by a long way! Note the TAL and CIT in the specs.
TAL=Talbot and CIT=Citroen if you hadn't guessed!
One thing about the Solex 34CICF on the Murena 2.2 that might catch you out, it doesn't
appear to have an idle mixture screw. It does but it is not visible as with older carbs.
The reason is that tighter emission controls were just coming in at that time, and these
carburettors were more accurate, set up correctly and then 'sealed' to prevent tampering.
The mixture screw is buried in the base flange going horizontally left to right, is gripped
with threadlock to prevent movement and may have a sealing plug fitted to prevent access to
it. If you should need to alter it (although you might question 'why?' as it should never
need it and the problem will probably lie elsewhere) you will have to dig out the sealing
plug if it's still there, and then when you turn the screw you must make tiny adjustments
with plenty of time to settle between each one, as these are much more sensitive than the
older carbs. (with external mixture screws usually gripped with springs around them to stop
them turning on their own). In fact you really should have it on a gas analyser as you won't
really be able to detect when the emissions are correct otherwise. These are not
carbs. and engines that can be tuned by 'ear' any longer as with older cars.
- My Murena Weber/Solex downdraught carburettor is worn out. What can I do?
First, for carburettor spares, one place I have found very good is Eurocarb Ltd, Reading.
They are mainly Weber and Dell'Orto specialists but worth a try for Solex.
If you have a 1.6 Murena with a Weber carb. there are usually plenty of spares still
available to overhaul and repair it when necessary, and there may be the odd place who can
still sell you a new carburettor if you wish. Seal and gasket kits are certainly
If you have a 2.2 Murena then the problem is that Solex spares are now difficult to get hold
of, although it can be possible. Try Eurocarb or Webcon, Sunbury who although Weber agents had
some stocks of Solex spares too (and jets are often common anyway). There may even one or two
places who say they can supply new Solex carbs. (old stock probably) but please bear in mind
what I said above about the correct specifications. Again, seal and gasket kits are still
available. If you change the needle valve, please make sure they are exactly the same as any
change will alter the float level and cause problems.
If you can get an original replacement, then this is usually the best option, since the
manufacturer spent a lot of time and money getting it right in all respects. However, this
may not be possible, or you may want to try and improve the carburation, at the same time as
replacing it. However, you should remember that the orientation of a carburettor is very
important. You cannot fit a carburettor from a longitudinal engine to a transverse engine,
or if you insist, you must rotate it 90 degrees, so it faces the same way relative to the
direction of travel, as it did originally. Also when changing to a different carburettor, it
is always best to have the car set up professionally, preferably on a rolling road. You will
then know that it will drive correctly in all conditions, not be too weak or rich at any
point, both which can damage an engine, as well as giving inferior performance and fuel
consumption, and probably causing excess pollution.
The Solex 34 CIC can be replaced by a Weber 34 DMTR which is the carburettor fitted on many
Citroen CX's. However, there are many different specification 34 DMTR's available and since
the venturis are cast-in unlike many Weber where the venturis are changeable, they cannot be
removed or replaced so the problem has been trying to find out which one is a direct replacement
or at least, is as close as possible to the specification we need. Some will physically fit in
every way (provided you have the later throttle linkage - the early linkage will foul the choke
diaphragm) and one even has almost the ideal venturi and jet settings etc., but it has no
vacuum take off for the distributor advance mechanism. Until I can give a definitive answer,
I won't recommend any. I have seen a number of different versions of this carburettor
fitted to Murena, but none so far have been correct in all respects which means they needed
some modifications. It may be that there is no ideal replacement, and whichever is chosen it
will need modifying. If this is the case, then we need to find the one that needs the least
If you have found a 34 DMTR that is just right in every way, please let me know the
specification and part numbers, so I can pass on the information. Once I have found the best
option, and what changes, if any are required, I will put the details here. Watch this
space, as they say!
By the way, if there are any Murena still around with the Tagora 2.2 down-draught inlet
manifold and either the 35 TMIMA or a Weber 38 DGMS or DGAS, these will never work! These
carbs. are for longitudinal engines and won't work on a transverse one!
- Can I fit twin side-draught carbs. to my standard Murena 2.2?
The twin side-draught carburettors fitted on Prep 142's and 'S' models required a special
manifold and air box as the space is quite tight. You can obtain an alternative manifold
and modify it to fit as some owners have done, but usually these other manifolds are 'flat'
whilst the original was tilted up at 15 degrees and importantly the left carb. moved over to
the right, so that the carburettors and air box fitted above the fuel tank. A plain horizontal
manifold will mean you cannot fit an air box, and the intake on the first venturi is almost
right up against the side of the tank. You might consider not fitting an air box anyway, or you
want to fit 'pancake' type filters, but please realise that the air at the top of the engine bay
is extremely hot and you do not want the engine breathing this! The original air box was
connected to the original air filter above the transaxle, which picked up cooler air from
low down behind the block. Cool air is denser and provides more power as well as helping to
control the engine heat.
The second point to remember, is that these carburettors are unlikely to give you more power
than a good twin-venturi down-draught set up, but you will use more fuel! You certainly do not
want big side-draught carbs. say 45 or 48 DCOE's. The original Solex were only 40's for good
reason. Power comes from having good breathing, and a better camshaft is needed before going
up in carburettor size. The Holbay Tornado 58C fast road cam profile is better than the 'S' cam
but will still happily produce the power with a twin-venturi down-draught carb. There is also a
restriction in the exhaust port that will ultimately restrict the breathing of a standard head,
and it cannot be opened up since you will go through to the water jacket.
If after all this you still wish to fit some twin side-draught carburettors, then the obvious
ones to try are either Weber 40 DCOE or the Dell'Orto DHLA. Since the supplier is unlikely to
know the Murena S spec. you should give them the Solex specifications and that may help them
to provide an equivalent set up.
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This was last updated 31st August '17