So here's a bit more info about my device. The picture attached shows my #2 prototype board, the one I'm currently using on my car.

As can be seen, all components are leaded so it does not require any special tools to build. The LED 7-segment displays are fitted on the rear of the PCB. Essentially all components are modern deriviatives of 1980's era components.

The big black device in the middle is an 8052 microcontroller. This can be programmed through the connector seen on the left side. The lower part of the board contains the analogue circuits resposnible for detecting the signals from ingition and crank sensor. To the right of the microcontroller is a circuit that does some basic filtering of the signals before supplying them to the microcontroller for actual measurements and calculations. There is a voltage regulator on the board responsible for the 5V supply to the system and a separate one supplying the 9V supply which is used to generate a permanent magnetic field in the crank sensor coil. Since the crank sensor is unmagnetic, it needs a constant DC current flow to generate a small amount of magnetic flux. When a notch in the flywheel passes by, the flux is distorted and an additional current is generated, and this additonal current is detected in the analogue circuit. A fuse and protection diodes protect the device from voltage spikes and reverse polarity. The top part of the board (unpopulated) contains an isolated RS232 interface which I'm still working on.

As mentioned, the basic idea is to measure the time between the ignition and the crank sensor triggering, divide that by the time between crank or ignition signals (1/RPM effectively), and multiply by 180 to the the advance in degrees. There's also a factor of 28 degrees to subtract from that number due to the fact that the crank trigger is not at TDC on the flywheel.

There are two triggers per revolution of the flywheel since there are two notches in it. This corresponds to the four trigger points inside the distributor, which runs at cam speed, i.e. half the crank.

I'll give an update later explaining how I am driving the crank sensor and getting useful signals out of it.

Oh wow a small subwoofer sounds genius. I probably will have to do an overhaul of most of the looms at some point. There's several weird electrical issues and the grounds seem fine for as far as I can see. So for the moment I reckon I'll just lay down a new set of speaker cables to at least solve the crosstalk.

I attached a picture of how the place that did the mot solved the reflectors for the moment. I can't visually see anything wrong with the original ones but the problem is that they don't bounce back enough light anymore according to the measurement tool. Well there's a clear difference between the new reflector and the original ones.. Also, it's not that he's making any significant profit from selling me those so I didn't question his judgement on that ground. When you say that Simon sells reflectors. Do you mean that that square under the reverse lights can be replaced?

Thank you for your kind words.

I still have some challenges - especially with getting the client IP address logged, which is a great resource for admin approval of new members (which seems to have gone a bit wild since the upgrade)

Once I have stabilised it, I will then begin working on miving everything to the new(we) server and upgrade to the very latest version.  Happy days :-)

/Lennart

Great to read your update.

I like your idea about the equalizer-amp and a bluetooth module. I have modified a Blaupaunkt radio with a built-in module that allows a signal pass through when not playing. Getting decent sound quality in the Murena is a bit challenging, one issue being that even with bigger speakers, the rear is essentially open which means that the low end "short circuits" back to the rear of the speaker. I think the door speakers will work much better in this respect, but I don't have them, and like you, I prefer not to. I've worked on making a very compact "subwoofer" that fits above the glove compartment...

Rear reflectors are available from Simon, but could you post a picture of exactly what did not pass?

Been a while since I posted.
So far my headlamps still work.
I had the switch for the interior fan burn through earlier this year or at the end of the last. Fixed it recently for the MOT with a flip switch. I can now turn it off and on which is really all I did with it anyway but I plan to do a more elegant fix in the future at some point.
I also fixed the leaking sunroof. Only took me a few years to accomplish that 🫣.
Everyone kept telling me that they thought it wasn't possible to fix it and that I should just kit it shut or replace the whole sunroof. In the end what worked for me was actually really simple. I bought 20 meters of closed cell EPDM tape something like 10mm wide and 5mm thick and taped that to the glass pane instead of the frame and glued the ends together with a glue that stays flexible and that so far seems to hold up very well, even with frequent opening and closing. I installed some new second hand 80s door speakers. It's a bit of a shame that the previous owner fitted speakers there. Also there appears to be crosstalk so it's essentially giving me mono output. I also picked up a working 7 band graphic equaliser/booster that I'm hoping to pair up with a hidden Bluetooth receiver to get old school looks with modern features.
Oh and the rear reflectors didn't pass MOT so they stuck extra reflectors on the rear 🙁 safety first though 😕

Thanks for sharing these pictures and reflections, Youri! It's amazing to see documented what can be done to these engines without transplanting turbos or whole new drivetrains on the car. The little things make all the difference. You know I love to see what you are doing. Thanks for sharing to a somewhat wider audience.

Seeing your bottom end work reminds me I have a block in the back of my garage which deserves some attention some day in the future

I know you will be increasing compression on this engine. I wonder if you could elaborate on the advantages and risk of doing so, and what you will do to avoid detonation and overload of the bottom end?

As the block is still in the machine shop for boring and initial skimming I have put some time in determining the camshaft for this engine.

The powerband of this engine is determined to be between 2500 - 7000 rpm, as the bottom end will not be able to sustain anything higher than that, this means that we can stay below 290 degrees of duration, any more than 290 would be pointless.

Scanning through the profiles I had available to me the JRD Number 1, which was originally designed for Sports 2000. Is a very suitable camshaft. 285 degrees of duration, a tighter LCA at 106 degrees and 66 degrees of overlap will make for a very broad powerband, lift is at 7mm on the camshaft.

Ideal lift is calculated to be between 20% and 25% of the diameter of the valve, as the valve lift of the JRD camshaft is 9.6mm, and the size of the intake valve is 47mm, the end result is a minimum amount of lift required of 9.4mm.

Enlarging the intake valve to 47mm means that the exhaust valve will have to be enlarged as well to stay at a healthy ratio, 85% of the intake results in a 40mm exhaust valve.

The camshaft has been ground out of a new original one and is ready for assembly.

Finally I have found the time to start a topic about the project I have been working on for quite some time, a better engine for my 2.2S.

The objective; 90hp per liter, which is going to be a bit of a challenge, quite some work has been done and will have to be done to get to this number.

I have first started identifying possible improvements to the engine block and rotating assembly, wich have resulted in the following points that have to be addressed:

- The rods are heavy and out of balance, there is quite some difference in weight between the 4 rods.
- The crankshaft is out of balance.
- Oil return path is not very fluid, a lot of obstacles in the way.
- Oil feed to the oil filter housing has a nasty 90 degree corner it has to go through.
- The flywheel is too heavy and not very well balanced.
- Engine block is not stiff enough in the area of the main bearing caps.

First I have started addressing the oil issues, which a die grinder fixed (visible in the attached photos).
I then proceeded to clean up and balance the rods and crankshaft.

In the next installment I will start working on other things on the block that will have to be addressed.

Yay! - I have today (Oct 3rd, 2025 managed to upgrade the forum to version 2.0.19 - which is the newest possible on this o;ld server (due to dependencies on the PHP and mysql versions).

The end goal for this is to move everything to my newer server which is already in place and more or less ready - and THEN upgrade to the latest posssible forum software - which will have a slightly different look, but more on that later. :-)

All the best to all !

Lennart Sorth

I have just logged on Lennart and seen the 'new' Matra Forum, and like Anders wish to congratulate you on it.

We know it is the place to go to, for all Matra owners wherever they are in the world, and has been a great resource for Matra owners all these year.  Long may it continue.

Roy

Back in the old days, tuning ignition timing was a matter of replacing weights and springs inside the distributor and by trial and error on the road assisted by a strobe light, determinng the optimum advacnce curve. When our dear Murena's came out, the there was specialised equipment available for mechanics to test the advance mechanism of distributors to ensure they were within specs. Today, of course, digital is the way forward and you can buy aftermarket distributors with bluetooth interfaces having replaced the weights. Tuning with these devices is best done on a rolling road. The potential is great!

But even in 1981, when the first 2.2 engines were fitted to the Murena with mechanical Bosch and Ducellier distributors, there were some electronic tools available, and these were in fact used on the Murena. We know, since the 2.2 was fitted with a crank sensor connected to the diagnostic connector. It was there for diagnostic purposes as the picture from my "Nachtrag der bedienungsanleitung" for the 2.2 shows. Note the "Geber für Zündzeitpunkteinstellung" and the "Diagnoseanschluss"!

I started wondering, a few years ago, about this sensor. How was it used? Noone I have talked to has seen a device that uses is. So was this just a meaningless item on a feature list? Perhaps! Yet, I kept thinking that it should be quite easy to get a signal from the crank sensor and compare the timing of it with the timing of the ignition signal, measuring RPM and advance.

Well, "Quite easy" turned out to be quite a project.

I have a fully working prototype now and will use this thread to document the way it works and how you can build one yourself. The picture is from when I was debugging my design in my lab. I will post pictures later of it working on my car and details about the design.