MatraSport Forum

Hi everyone !
I had to remove my 230hp turbo engine from my car (thanks to new french tech control  :'( ) and I'm working on a "near genuine but spicy" 2.2 engine  8). Sooo, I'm looking for a good camshaft.
 Everyone is talking in great worlds about Holbay 58C one, but it seems that no one can sell it now ...
 I have most of sport camshaft specs ( S, Politecnic, Sodemo Gr4, .....) but not this one's  !
Is someone can tell me the specs of this camshaft ? I think it would be the best choice for my car ...

Hey there! Welcome to the forum. Sad to hear about your contrôle technique experience. I have the following specs on file:

Specs:
Std:    Lift 6.5mm          Timing 19°12' 56°48' 54°48' 13°12'
Period (Inlet) 256° (Exhaust) 248°       Overlap 32°24'
Valve clearance (Inlet) 0.2mm   (Exhaust) 0.3mm

'S':    Lift 7.4mm          Timing 27° 72° 69°30' 29°30'
Period (Inlet) 279° (Exhaust) 279°       Overlap 56°30'

Holbay: Lift 7.06mm         Timing 39° 77° 79° 37°
Period (Inlet) 296° (Exhaust) 296°       Overlap 76°
Valve clearance (Inlet) 0.25mm   (Exhaust) 0.3mm

Sodemo gr 4:   Lift 7.75mm  Timing 30° 86° 78° 42°
Period (Inlet) 296° (Exhaust) 300°       Overlap 72°

I agree, the Holbay is a great cam shaft. Although it has less lift than the S-cam, the overlap helps the airflow and the performance might be even better. Also, it runs very well with the standard Solex 34CIC carb.

There was a few made recently. Contact Roy at roy@matraclub.org.uk as I think he knows who has the tooling for it.

thanks for this so fast answer !!! Do you think this camshaft is only good for a single carb use (and maybe 2x40ADDHE), and sodemo better for bigger carbs with high revs ?

You're welcome :) No I think it's fine for a set of twin carbs, but if you want to convince the car is standard, why not use the single double barrel Solex? I'm running a Holbay on a pair of Weber 40DCOEs

I will use a genuine carb for the moment ... but I'm working on a exact "S" replica manifold  3d printed made of ULTEM material ... next level ...  ;D

That sounds VERY interesting! :)

3D modeling from an original manifold is on the way ( near finished), and Ultem is loaded  ;D
I will be able so cast in aluminium too (with lost PLA method), but first step will be to print the prototype .... validate it, and go to Ultem.
I also made a "Matra Sport" camshaft cover for 2.2, the prototype is validated and ready for aluminium casting (casting sand method).

Do you think a camshaft with all Holbay specs, but with a little bit more lift (maybe 7.2 between holbay and "S") would be better ?

I have a genuine 2.2s but it had been changed to a single Solex by a previous owner. (who hadnt kept the original carbs manifold or airbox - Arrrggghhh). trying to get original replacements is almost impossible.
I bought one of the 4 new cams that Roy had made to a new spec, trying to get the best of all the previous versions.
Mine is installed but not running yet . There is only 1 running i know of so far and i believe Roy has driven it and that he has previously owned both standard and Holbay versions so would be a good person to ask his opinion.
Like you I wanted revert to original ‘S’’ but also it be reliable. I believe the Dellorto is a better set up and more reliable than the Solex so that is what I will be fitting. I have also made a reasonable attempt at a new inlet manifold, made from flat plate and tubular alloy. I had four of these and I think Roy still has a spare available. They were fairly cost effective and simple just not quite as curvy as original. i will try and get a picture over the weekend.
Ian.

Hello philiping,  The first thing you need to realise is that the Matra marketing department lied about the horsepower of the original engines.  The engines were tested by the factory for the original specifications and these figures were in kilowatts as is normal in France.  A standard 2.2 produced 84.32 kw, the 'Prep 142 ' was rated at 101.4 kw and the genuine 'S' was rated at 100 kw. (Check the certificates of Conformity)  However the marketing people then used a 1.4:1 conversion factor for horsepower to kw which is wrong and this gave misleadingly high horsepower figures.  Also they did not state whether this horsepower was PS or bhp, but since they generally talk of horsepower DIN, that is PS... NOT bhp.

If you convert the original kilowatt figures recorded to bhp correctly, then the standard 2.2 produces 113 bhp, the 'Prep 142' uprate gives 136 bhp and the genuine 'S' produces only 134 bhp.  All this has been on my website for some years.

The Holbay reprofile gives a lovely camshaft which easily produces as much performance as a genuine 'S'  and on the road is better.  I know, as I have driven both for many years.  Furthermore the Holbay reprofled cam can be used with either a 'twin-choke' down-draught carb. or two twin side-draught carbs. and the only real difference is the fuel consumption.  On a down-draught carb. it will easily top 31 mpg on the open road, and not generally drop below 25 mpg even around London!  (that is where I live so I have proof if anyone needs it)  With two twin side-draught carbs. the consumption will always be slightly less on the open road, but around town it can drop below 20mpg!

I once roller tested my Murena with Holbay 58C cam still using the down-draught Solex, and it gave 140 bhp, so you can see it slightly out performs even the 'Prep 142'.  Unfortunately Holbay no longer exist, which is why you cannot get a Holbay reprofile from them, but that is not to say you could not get a similar reprofile from someone like Piper or Kent cams.  It is simply a 'fast road' camshaft reprofile.

I did not like the 'S' profile as it has more lift but less duration which means the ramp angles are steeper, and since the lower lift but longer duration Holbay profile produces more power I decided a better cam would have more lift as well as longer duration.  Working with Piper we came up with a high lift long duration profile fast road cam which produces a superb engine as I know from having driven the first one I built.

I should also point out here that the Politecnic 'maxi-route' profile which originally appeared to be a Gr.4 cam in their leaflet (of which I have a copy somewhere) is unlikely to be as good as it has a similar duration but less lift.  (7.75mm lift compared to 8.30mm lift for our Piper and 296 inlet/300 exhaust degree duration compared with 298+ degree for both inlet and exhaust duration on the Piper, which they measure from 10 thou open to 10 thou before closed)

Again, I have driven a Murena with the 'maxi-route' cam which is stamped 150cv suggesting it is actually rated 150 horsepower but with optimum set up can give around 155 bhp, and the Piper is better.  This is with both using the standard valves.  To get a true 184 bhp Piper say the engine would need to have a lot more lift (maybe 9mm cam and over 12mm valve) and bigger valves or 4 valves per cylinder, higher compression, combined with optimum fuel feed from big carbs. or fuel injection and unrestricted intake, and even those special ROC engines only gave 200 bhp with a £2,000 special cast twin cam cylinder head and race build and preparation!

Finally, if you have a standard 2.2 engine, then you should get the flywheel lightened as it is too heavy for the Murena because it has the standard Tagora 2.2 flywheel!  The lightened flywheel improves pickup noticeably.

Roy

wow ... and 8.3 lift does not make  piston/valves interferences ?
So my idea to make a cameshaft with all the Holbay specs, but a little bit more lift (7.3) is not so bad ?
I've already worked on my flywheel : now it's 8.2kg and balanced with all rorating parts. As you said, it's a must do for this engine !

Has anyone here rebuilt a 2,2 engine with a sportcamshaft and instead of single or twin carburaters used manifold from Peuget 505 turbo engine together with Bosch LE jetronic injection or similar simple system?
If I compare with experience from Opel CIH engines in GT,Manta Ascona there is a big difference when the engine has fuel injection system. More quiet and smooth behavior, save fuel and always starts with warm engine.

//Mattias

Would love to see a picture of the "Matra Sport" camshaft cover when it is finished.

I have a "Politechnic" camshaft cover which is O.K.  but a bit "agricultural"

Here is an old article for your interest/inspiration with some piston/valve interferences mentioned during an engine rebuild carried out by Roy previously for me. (Using the Camshaft stamped 150 CV from Politechnic).

Keep us posted of developments......................

I have the only car running with the Piper cam in it, unless Graham has been busy...? (do you have any events planned for next year with the Murena Graham? I am yet to see it in action...) It is good, very good, everyone who has driven it (who all have more experience of driving various Murena then me) says how good it is.
Here are some videos of it...
https://www.youtube.com/playlist?list=PLkkcMOq03tEgbCE2AzitiB7zyv-57QC0H

No, I originally measured the clearances between the valves and pistons when rebuilding Graham's engine some years ago, so we knew we could go with more lift when we had the Piper cams made.  The Murena 2.2 engine now rebuilt in Colin's car has our new Piper camshaft with 8.3mm lift (11.37mm valve lift) and still has some clearance when running, and as can be seen and heard on his youtube videos, it goes well and sounds really good. :)

Roy

Hi Colin, no I have not fitted the Piper Cam as per your engine yet. Too mean to replace the Mecapart Head Gasket again £££££ Hah!
Another "no" I'm afraid as nothing planned for next year as yet.  A few other distractions/responsibilities have popped up.
Keep you posted when it does happen though?

Graham

2020 Update:

I have now found my Politecnic brochure and the above specifications are not quite correct, so I would like to correct them for anyone else who is wanting to uprate their 2.2 engine, and is reading this thread.

The camshaft specification Anders lists above as the Sodemo Gr.4 cam is actually the data for the Politecnic Maxiroute camshaft and will only produce around 150-155 horsepower and cannot be a Group 4 cam producing 184cv.  The Group 4 Politecnic-Danielson kit which was supposed to produce 184 cv also had bronze valve guides and special sodium filled exhaust valves (for cooling) with twin concentric valve springs and special aluminium retainers. Whether these valves were larger and the head had a higher compression it does not say, but I suspect it did and also had a special high lift cam, higher than even the Piper 3777 because having spoken to experienced racing engine manufacturers, for this naturally aspirated 2.2 engine, the valves would need to be lifting over 12mm to produce around 185 horsepower.

We know that the Piper 3777 cam with 8.3mm cam lift and therefore 11.371 valve lift, plus wider timing will not produce more than approx. 160bhp so there is no way the Maxiroute cam with less lift could produce that claimed 184cv (181bhp) without extensive other modifications.  But the original Politecnic brochure does not claim the Politecnic-Danielson kit uses the Maxiroute cam.  The brochure simply lists what was available from them at the time and the options were:
1) Maxiroute reprofiled camshaft priced at 1,990 FF in exchange for your old cam.
2) Politecnic-Danielson complete Gr.4 kit priced at 7,500 FF.  (yes French Francs which shows how old this brochure is!)
You can see from the price difference here, that the Gr.4 kit contained a lot more as it cost approx. 3.5 times as much as the reprofiled Maxiroute cam!

Roy

I have the correct information on this matter.

The Politecnic Gr.4 set consisted of a special hemispherical head, with bigger valves, double springs, modified intake ports, small spark plugs and a wider exhaust.
It was delivered with a special camshaft, which was available in two stages, 184cv and 200cv. (these figures are real figures as on bench tests).

A few of these heads were made for the Rallye Monte Carlo cars, and later for some rallyecross operations.

Whatever was left they put for sale on their brochure, (in numbers not more than 2 sets). The last set was bought by us in 2001 and put on a Murena S.
(The photos of the engine bay of a Murena S with double Dellorto's is in fact our car).

These are really potent kits and are not comparable to whatever is on the market today.

Thank you for your reply and the confirmation of the true facts.

When you say the photos of the engine bay are of your car, what photos?  I see no photos here, or are you referring to the photos in that an old Politecnic brochure?

Roy

Roy,

The photographs of the Murena S engine bay on the Politecnic website are in fact of our Murena.

But it seems the photograph is gone, there are still some photo's on the "Moteur complet" page (the right one, with the carburettors, it is the special head.)