Carburettor settings

[roy4matra]

I have recently been helping a club member, via email, set up his Murena 2.2 carburettors since they obviously weren't correct.  Now this is patently not the ideal way of tuning any car, but surprisingly you can at least get close, if the feedback on changes are informative, the basic settings were not too far out, and you only change one thing at a time; and you understand what effect the different variables have of course!

I would be grateful for information on other 2.2 set-ups and how well they perform.  If as many of you as possible that know your details, can provide the following information, maybe we can arrive at a good basic set-up, which I will then put on my website FAQ, so others can get a good idea where they should start if they wish to check or tune their car.  I would prefer the figures initially by email, rather than here, so the details don't get swamped by the large amount of discussion I think this will generate!  Or if you send the details here could you also email them directly to me.  Thank you. (roy@matraclub.org.uk)

I would need to know Carb. type and specs. (e.g. Weber 40 DCOE 15 or Dell'Orto 45 DHLA or whatever) and the following sizes / numbers:
Venturi
Auxilliary Venturi
Emulsion Tube
Air Corrector Jet
Main Jet
Idle Jet
Idle Jet Holder (Dell'Orto)
Pump Jet
Pump Jet Bleed or Discharge (Weber)
Needle Valve
Floats
Float Level Setting
Idle revs. number of turns of idle mixture screws out from closed, and how smooth the idle is.

Also important is the spec. of the camshaft fitted and static timing, and information about how it performs - e.g. pulls smoothly and strongly low down and in the middle range but runs out of steam at 5500 rpm; or hesitates on pick up around 2500 if throttle floored but O.K. if throttle opened slowly; or runs well throughout range, top revs 6500; etc.  Please be honest - if your car is good, that is great, but I know many are not, and this may eventually help those to get them right. (this is another reason to email me directly - you may not want to admit on the forum what you really think of your car.  All information to me will be kept confidential)  Power and torque figures if you have them would be useful, although I expect most won't know these unless the car has been on a rolling road.  Overall fuel consumption is also helpful as it gives some idea of how good the set-up is too.

Thanks for any help in this quest.  (Of interest maybe, our next magazine will have the first article on Murena 2.2 and tuning...)

Roy

[Anders Dinsen]

I think that's an excellent idea and initiative, Roy. I would send you my data if you didn't already have it

Some does ignition tuning and it can mean a good deal for idle smoothness, I've learnt (by reading books!), so you might want that information too. E.g.:

* static advance (without vacuum @ 1000 rpm)
* max advance
* max advance reached at X rpm

- Anders

[roy4matra]

I think that's an excellent idea and initiative, Roy. I would send you my data if you didn't already have it

Some does ignition tuning and it can mean a good deal for idle smoothness, I've learnt (by reading books!), so you might want that information too. E.g.:

* static advance (without vacuum @ 1000 rpm)
* max advance
* max advance reached at X rpm

- Anders

Just to add to what I've said, and as Anders has highlighted, I already have the standard carburettor settings, for both 34CIC down draught and 40 ADDHE sidedraught carbs.  It's non-standard ones that I would like to have information for, so that I can hopefully help with aftermarket tuned set ups.

Any additional information such as those indicated by Anders is always welcome.  Thanks.

Roy