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 81 
 on: April 14, 2018, 04:59:33 pm 
Started by Abe - Last post by roy4matra
Hi Abe,
better use 45 or 48 Twin choke Webers or Dell 'Orto's  and a Politecnic / Sodéma camshaft. Only 40 Twin choke carburettors are too small and won't bring that much performance.
 For the airbox , you can copy the Murena S airbox . You can also modify a Alfa airbox , but is is rather boig and you don't have much room there.


I'm sorry but I disagree with a lot that has been said in this thread.

The first thing is that the Murena 2.2 needs a much better camshaft before you start fitting bigger and twin side-draught carbs.  For instance the Prep 142 or 'S' will actually run just as well with the original single progressive down-draught Solex and give much better consumption too.  The Prep 142 and 'S' camshafts are not that great really and the original power figures were over stated.  As explained on my website, the standard 2.2 actually produced 113 bhp, the Prep 142 gave 136 bhp, and the 'S' gave 134 bhp.  I have proved that the Holbay Tornado fast road cam profile with a standard down-draught Solex 34 CICF can produce around 140 bhp and give 28 to 34 mpg which is better than either the 142 or 'S'.  If you want proof, check with Anders Dinsen who had my Prep 142 with the standard down-draught carb.

So if you want greater power than the Holbay or equivalent fast road cam profiles you will need an even better cam profile first, AND then you might need the twin 40 or 45 DCOE or DHLA twin side-draught carbs. but then you will have a further problem... and that is the manifold to put them on.  The original Prep 142 and 'S' had a specially designed inlet manifold which moved the LH carburettor over to the right and lifted them both such that the intake was above the fuel tank and the end throat was not seriously restricted compared to the others, and a decent air box could be fitted which picked up cool air low down.  This is necessary since allowing the engine to breathe the very hot air from the top of the engine compartment is bad.  The special manifold also included a coolant extension on the RH end which none of the non-genuine inlet manifolds provide, so you will have to make up something yourself.

All the non-original intake manifolds including the Politecnic one are not good enough and are a compromise which will seriously restrict the intake and therefore the power produced.  Furthermore some of these non-genuine manifolds cause fitting problems with other items such as the coolant pipe under the manifold, and dipstick tube; and all the modified engines with twin side-draught carbs. will drink a lot more fuel and will often drop into the teens when running around in urban environments.  Only on long runs with a large portion of cruising will the car produce 28 mpg or above.

The Politecnic cam was not available last time I checked - he might have your existing camshaft re-profiled but then you can get that done here and cheaper.

As for the  2.2 engines modified by SCU - I have never yet found a decent one!  They are all not much better than standard if indeed they are better - many are actually worse, and they use far more fuel too.

If you don't understand how a poor intake can seriously affect engine power then ask Titus who has seen 6-8 bhp differences for relatively simple difference in the intake system.  And you can't make and fit an airbox similar to the Prep 142 or 'S' on the twin side-draught carbs. fitted on a non-original manifold as there will be no room.  You might just a get very thin 'pancake' filter on the left hand carb. which is almost up against the fuel tank; but these are restrictive and again you will be picking up the very hot air from the top of the engine compartment.  Not only does this restrict the power (hot air contains less oxygen) but the hot air means higher combustion temperatures and they are already hot enough without adding to it.  This can be one reason for many of the failed heads or gaskets.

Roy

 82 
 on: April 07, 2018, 05:36:52 pm 
Started by Abe - Last post by Colin
48mm carbs will be too big, the choice is betweem 40 and 45s. My car came with 40s and now has 45s, with a 36mm choke, one can fit a 36mm choke into a 40mm Dellorto (I know nothing of Webers). My theory was that the venturi effect will be greater on a 45mm carb, with 36mm choke, this should increase efficiency, not necessarily power output. The other reason for the 45s was as we did not know what sort of performance we were going to get with the new cam, it made sense to go bigger. 40mm carbs are good for over 160bhp, and you are unlikely to ever get the 2.2 engine up that high. 
Ian Ratcliffe's engine will be the same spec as mine, but with a different manifold and (my old) 40mm carbs, so it will be interesting to see the differences in power and torque. Here are my numbers....

matra RR by c162ujf, on Flickr

 83 
 on: April 07, 2018, 03:20:42 pm 
Started by andy800 - Last post by andy800
hi all , I,m looking for a bagheera rear reflector panel , in red , which was from later cars , has anyone got one they would like to sell or know of one , its the last thing I need for my restoration ,   pm or post , many thanks andy

 84 
 on: April 06, 2018, 09:34:35 am 
Started by Johan Edström - Last post by Matra_Hans
You have not got much response on your question.

Personally I find the price of 10.000 Euro in the high end for a car that has not been on the road for almost 35 years (you might have to change gaskets, hoses etc.), however on the plus side is the very low mileage.
However try to check on Mobile.de or ebay-kleinansige.de what is on the marked and at what price.
Regards Hans

 85 
 on: April 06, 2018, 08:09:11 am 
Started by Abe - Last post by suffolkpete
Sports Cars Unlimited converted a number of cars to Dell'orto DHLA 45, the setup looked very like Colin's.  There may be a few of those manifolds kicking about somewhere.  Don't know what camshaft was used for these conversions.

 86 
 on: April 05, 2018, 09:30:45 pm 
Started by Abe - Last post by Colin
I agree... Just putting bigger carbs on will not do much, as the valves will still open the same amount and for the same amount of time, so the engine can not do much with the extra fuel and air avalible.
Finding hot cam shafts is so difficult that Roy got 4 made last year, by Piper, they were a bit expensive, but  my standard cam was worn beyond repair. The combination of the new cam and twin Dellorto DLHA45E carbs is good, but finding a suitable inlet manifold is also not going to be easy, my car came with a Politecnic manifold, which is just short enough to fit some air filters, but I do know or others which put the carbs so close to the fuel tank that this is not possible.
Here is my setup.
IMG_20170527_153759794_HDR by c162ujf, on Flickr

 87 
 on: April 03, 2018, 05:27:03 pm 
Started by TELBOY - Last post by TELBOY
Thanks for the photo oetker..great help Smiley

 88 
 on: April 03, 2018, 05:25:10 pm 
Started by TELBOY - Last post by TELBOY
looks evil

 89 
 on: April 02, 2018, 11:18:57 am 
Started by Abe - Last post by suffolkpete
I'm assuming you already have the Dell'ortos and want to use them.  Fitting twin carbs on their own won't make a huge difference to the performance and might actually make things worse at low revs.  You need to use an 'S' camshaft or its equivalent.  The side-draught Dell'ortos won't leave you a huge amount of space for an air box, probably best find a suitable pair of very slim off the shelf air filters.  When you've done all this, get the carbs set up on a rolling road by someone who knows Dell'ortos.

 90 
 on: April 01, 2018, 04:58:45 pm 
Started by Abe - Last post by speed pete
Hi Abe,
better use 45 or 48 Twin choke Webers or Dell 'Orto's  and a Politecnic / Sodéma camshaft. Only 40 Twin choke carburettors are too small and won't bring that much performance.
 For the airbox , you can copy the Murena S airbox . You can also modify a Alfa airbox , but is is rather boig and you don't have much room there.

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