The voice of an experienced mechanic understanding the nature of root causes! Thanks Roy for being so active around here

That sounds like they have the T-Piece sizes the wrong way around!  Maybe the one they supplied was 13mm/10mm/13mm when it should have been 10mm/13mm/10mm.


The T-piece that has a fastening to the bulkhead, 0032602000, and has one hose to the vacuum storage tank, the opposite one to the white vacuum valve at the front of the car, and the third centre connection goes to the one way valve that is connected to the inlet manifold, has connection sizes 10mm/13mm/10mm.  The 13mm connection has a short hose to the one way valve, which is the same item as the brake servo one way valve, 0030581600.

If you simply purchase a standard 10/13/10 T-Piece which can be bought for under £5, you can fasten it to the bulkhead with a cable tie.  The original T-Piece fastening often breaks off anyway and has to be fastened that way in my experience.  A 10/13/10mm T-Piece can easily be found on the internet or from AFS (Advanced Fluid Solutions) or on eBay, or Mercedes used to have one available which I have the part number for, if you can't find another.

Roy

Once the carburettor was running properly and the tension on the throttle cable was correct again, I had to tackle the vacuum supply. The T-piece (split supply vacuum control and vacuum tank) was brittle. So I ordered a new part from my usual dealer.
However, the diameter of the connections to the front and to the tank is much larger, but the connection to the check valve is much slimmer... So I carefully applied some silicone grease to the old vacuum lines on the T-piece and Teflon tape on the other side towards the check valve, and sealed it with a clamp.
It worked. I took it for a test drive and on the way back it started to run unevenly at idle speed. I got out and heard a loud hissing sound.
The vacuum hose couldn't withstand the increased tension and ruptured.
Now I'm considering whether to replace just that one or all of them. At the dealer, a 40 cm piece costs €10. That adds up to quite a few pieces and will probably only be available by the metre. But what is the correct designation for the right metre goods?

Many thanks for any advice.

Getting on the road is great. Problems show up, but I'm glad to hear your's solving it. I'm still working on getting to that point.

10 degrees on the standard cam makes sense. The period is short and there's little overlap on that cam so the fuel mixture in idle is good. You're probably running 800'ish idle? I have mine at 15 with the Holbay cam, which makes for a decent idle at 1100. It's huting a bit, but that's probably due to the high overlap on the cam and my cylinder head - it most likely short circuits a bit of fuel out the exhaust during idle. I have an AFR meter with a wide band oxygen sensor in the exhaust so I know the mixture is correct now.

I considered fuel injection years back. Most ECU's come with some sort of ignition controller and eliminate the distributor as they run wasted spark configurations with two coils. From an engine management perspective, that's a better system. They usually, however, depend on both a crank sensor and a cam sensor, so there's a bit of work involved and it will be completely custom. I'm not going that route, but staying with the sidedraught carbs. There's more performance to be gained by working on the airflow in the head, especially enlarging the inlet valve seat inner diameter. About the original distributors, in principle they can be tuned to do anything by replacing springs with other springs, but it requires a complete rebuild every time you want to try something different. The original Bosch has an advance curve that suits the original cam only (and vacuum takeoff from the original Solex carb). I have used it on my Holbay cam, but it will never be perfect, so I'm going to change eventually so that I can tune it to the cam and head.

/Anders

Hi Anders,

Yes, it's starting and running great now. Before that I had a few issues with the engine. After some searching it was because of a dying alternator. When I put the spare in almost everything was solved!  I had some wire connectors on the ignition coil getting loose while running the car. I change the old wire lugs with eye terminals and bolted these on the coil, problem solved.

And of course the right timing helped a lot. I found 10° advanced timing is the best. Above that doesn't work properly. I was advised 12° or more, but that's not working for this car.
For this standard engine the original ignition is fine. And I will rebuild the old alternator red so it can be used on the 2nd engine.

But most important is I can drive the car around. Because of that I found the clutch was slipping, so I replaced that. And I'm still finding little things to do.

For the spare engine injection project I think you are right to mount a 123ignition. I don't think the original will be working the best in combination with the injection and faster cam.
But first I need the injectors, all connectors, make a wiring loom and so on.

To be continued....

The objective of the cam is to time the airflow through the cylinder head by opening and closing the valves. There's a lot of theory and expeirence behind cam tuning, much more than I'm competent to explain, but I wanted to share these photos which Youri (Murena1400) has kindly shared with me and given me permission to post here as they show the channels the air is passing through when entering or exiting the cylinder.

The primary restriction on the 2.2 head is the inlet valve seat. The cross sectional area of the opening is simple to calculate by calculating the area of the circle inside the valve seat minus the valve stem circle area. The area of the valve opening is given by the lift of the valve multiplied by the valve seat circumference.

Increasing the inner diameter of the valve seat will increase both areas. Theory says that a restriction has effect on airflow when airspeeds become sonic as it's not possible to accelerate air molecules beyond the speed of sound. Remember that air flows into the head in pulses so the restriction can be said to "cap" the top of the pulses. Turbolence created by edges and the like also restrict a little, but generally turbulence in the inlet is desired as it assists mixing of air and fuel in the cylinder.

The pictures are of cut-throughs of an unmodified head.

Exhaust is even more limited as the exhaust valve (and valve seat) is significantly smaller. Exhaust restrictions affect performance far less than inlet on a normally aspirated 4 stroke engine.

Hi Henk, good to hear you finally got it reground, and also great that you have the car running again.

I notice you asked about ignition in the thread below. Have you considered converting to 123Ignition?

Classic Auto Elec in Tours, France stocks it for the Murena. It's the same distributor for all engine types, 1.6 or 2.2, you just have to choose the right distributor cap for the 2.2:

https://classicautoelec.com/en/electronic-ignition-matra/5130-6778-programmable-electronic-igniter-for-simca-1000-1200-1300.html#/180-tete_d_allumeur_a_sorties-droites/678-123_tune-non

I have run the standard 2.2 Bosch distributor on my Holbay and I've not yet converted to digital ignition advance myself, but I will since it allows tuning the ignition advance correctly to match the cam. Of course you can play with the timing springs in the distributor, but they're hard to find and even harder to replace.

123Ignition can be tuned over Bluetooth with an app on your phone.

Hi Guys,

Just wanted to let you know I finally got the regrinded camshaft back. This took months instead of weeks. As I was tired of waiting I put the other standard camshaft and head in, to get the car driving. Which it does! It passed the APK (MOT) and is working fine. There are a few minor issues which have to be taken care of, but I'm happy as it's going now.

The 2nd motor is been almost completely overhauled. The other head with the fast camshaft is mounted. I'm working on this motor so now and then. I want to try to convert this one to injection. For this I have the inlet manifold and fuelrail of a Peugeot 505 GTI turbo. The ECU and injectors are LE-Jetronic from a Peugeot 505 GTI 2.2 (non turbo), as well as the air mass meter and other parts. I hope to get this configuration working, but there is no hurry. When and if this works, this will be mounted in the Murena. if not, I've got another original inletmanifold and carburateur in stock.

Henk

 

Thanks for the information. I removed the cap and, lo and behold, it looks fine now. Thank you very much.

What an annoying problem. At least just one. Good luck getting it right!
/Anders