Caburator problems!

[jeko]

Hey Matra freinds

I've just got my Murena 2,2 some month ago, and I am now fighting with a caburator problem.
When the engine is hot (no choke), it dies if I, from idle,  presses the pedal to fast.
If I presses the accelerator pump immediate before pressing the throttle, it all works okay.
The accelerator pump has been adjusted so it is being pressed immediately, when the throttle moves.
The caburator has been separated, cleaned and a complete gasket kit has been fitted.

I am not quite sure about the ignition adjustment!
I guess the first mark on the Belking housing, towards the front, is the O.T point, and every mark is -2 deg.
The ignition is placed in the middle of all the marks, which should be - 5 deg.
Is correct?

The car is fitted with a KN filter. Is it possible that it gets to much air?

I can drive the car, but it is annoying that I have to keep the rewindings high when I have to start.
Does anyone have suggestion?
 

[Anders Dinsen]

Hej Jeppe

If you can drive it, why not drive it over to Bagsværd and we can take a look together... I do have time for that this weekend both afternoons, but can't promise to be able to leave the home, I'm afraid.

I don't think it should die on you even when running without the accelerator pump, but your ignition sounds incorrect. At idle with vacuum advance disconnected it should be advanced to -10 degrees. This could be your problem, I think. The little screw on the side of the accel pump lever can be adjusted to align the two sections of the lever - this changes the rate with which the accel pump is actuated and thereby the amount fuel sprayed into the venturi, you can try adjusting it a bit further:

http://gallery.dinsen.net/v/Murena/technical/carb/DSCF0022.JPG.html


The KN filter makes no difference, as long as all the air comes through the carb, it can't get too much.

Roy is the real expert on these matters, but I know he's busy preparing for the big meeting in the weekend, so I don't think we can count on him posting just now.

- Anders

[roy4matra]

I've just got my Murena 2,2 some month ago, and I am now fighting with a caburator problem.
When the engine is hot (no choke), it dies if I, from idle,  presses the pedal too fast.
If I presses the accelerator pump immediate before pressing the throttle, it all works okay.
The accelerator pump has been adjusted so it is being pressed immediately, when the throttle moves.
The caburator has been separated, cleaned and a complete gasket kit has been fitted.

I am not quite sure about the ignition adjustment!
I guess the first mark on the Belking housing, towards the front, is the O.T point, and every mark is -2 deg.  The ignition is placed in the middle of all the marks, which should be - 5 deg.
Is correct?

No, it should be 10 degrees before TDC, and since the marks are 0, 4, 8, and 12 degrees BTDC the flywheel mark should be midway between the 8 and 12 marks, static or idling, without the distributor vacuum connected.

The car is fitted with a KN filter. Is it possible that it gets too much air?

The volume of air in, is controlled by the throttle and the venturi size, so if the carb. is standard the only problem that you get from fitting a K&N Filter is that you will be breathing hot air from the top of the engine bay, when it would be better to have cold air from lower down as with the original air filter and intake system.

I can drive the car, but it is annoying that I have to keep the rewindings high when I have to start.
Does anyone have suggestion?

First, if the car is stalling when you snap the throttle open quickly, it implies the mixture is too weak and is not richening up fast enough.  The action of the pump jet has to be right, and it sounds like it is not, but the retarded timing won't help, so put the timing right first.  You don't say, but I assume you have the standard progressive twin venturi down-draught carburettor?  Is it the original Solex?

Next, do the revs. increase O.K. if you open the throttle slowly?  Can you see the pump jet spray as you open the throttle?  Is the float level correct?  Are the jet sizes correct?  In fact is the carburettor actually the correct one?  Please let us have the full spec. off the carb. so I can see if it right, as there are some wrong ones fitted to various cars that will never work properly!  The spec. should be 34CIC...  I want to see the rest of it please.  Also on the lower flange is a long number like 12345.000  What is this please? These will tell me if you have the right carb. or not.

Once I have these and know we are dealing with the correct carb. we can go from there.

Roy

[jeko]

Hi again

I have been struggling with the carb, and I have found the problem! Why do you always start at the wrong place? I have cleaned and analysed the carb several times, and I did find a missing hole in the new gasket, but it didn't help. I have checked the ignition but it didn't help. Then suddently I could hear a new sound from the engine. And then I found that the vacuum tube at the vacuum tank had a crack. After correcting this, the engine can now speed up from idle whitout problems. Of cause it all needs to be trimmed, but things is working and there is hope for the future.
Now I say to myself , why diddn't I think of that. Well, I have learnt a lot about the carb, and I will never forget to check the vacuum, so it was good for something.
Next thing to do is check all tubes.

To you Roy :
The carb is a 34CIC with the number 13116.000

Best regards

Jeko

[Anders Dinsen]

And then I found that the vacuum tube at the vacuum tank had a crack. After correcting this, the engine can now speed up from idle whitout problems.

Hej Jesper

Congratulations!
That was well spotted

- Anders

PS: I took the liberty to correct a small spelling mistake in your post, I hope you don't mind! 

[roy4matra]

... And then I found that the vacuum tube at the vacuum tank had a crack.

To you Roy :
The carb is a 34CIC with the number 13116.000

Thanks Jeko, yes that is the correct carburettor for the car.  As I suspected the mixture was too weak, and the cause was the split hose.  I'm glad you found the problem.

Roy