R107 450 1973 D Jetronic. Doesn't start - ignition timing problem?

[Graham]

Originally Posted by Frank Reiner

Graham:

Just a thought: 1973 may have a four pin amplifier (switchgear), which switches the ground side of the coil, or since it is non-North America, there may not be a switchgear at all, just standard points controlled ignition.

So far as I know, all 107 Djets had switchgear. The type changed several times. Doubt any came from factory with standard (Kettering?) points ignition, but I have heard of some who converted to that.

Sections 07.5 519/520 of shop manual cover description, wiring diagrams and testing of these systems.

https://www.startekinfo.com/StarTek/outside/11883/PROGRAM/Engine/107/M117_45/075-519.pdf

https://www.startekinfo.com/StarTek/outside/11883/PROGRAM/Engine/107/M117_45/075-520.pdf

The points and switchgear can be completely eliminated by installing a Pertronix 1885 plus a Flamethrower coil and wiring as described here:

http://www.benzworld.org/forums/r-c107-sl-slc-class/1714668-pertronix-install-without-switchgear.html

Making the Pertronix fit will need to be addressed with that distributor - But it should be same as the 1975 model which is addressed in this link:Pertronix install - 1975 450SL - Mercedes-Benz Forum

Depending on the type of switchgear, the wiring could be slightly different too.

[szamik]

Originally Posted by Graham

do you have two tubes coming to the vacuum pod?

Yes, I do.

Originally Posted by Frank Reiner

there may not be a switchgear at all

I have switchgear with 4 wires coming out of it.

Originally Posted by Graham

Sections 07.5 519/520 of shop manual cover description, wiring diagrams and testing of these systems.

Thank you for these diagrams! I checked electrical components and voltages "around" coil. Everything seems to work well..




Engine still doesn't want to start. It started just once if I pressed throttle to the metal, but in was running on maybe 2 cyl

I will check how plugs look like.


Again about ignition timing : Few photos, engine set up in TDC. Is that okey?:






Camshaft on 1 cyl



And at the end....
Timing marks on passanger side.


Could this be a reason why car don't want to start?





Edit:

Right. I checked plugs. 6 of them are clean but completly wet. Plugs from 5 and 1 cyl are burned and dry - probably on these cyl engine was running for a while. I think that is good idea to checked again trigger points. Maybe injectors are working at wrong moment. Also I decided to leave engine without plugs and with open throttle body for a night, because intake manifold is full of petrol - my fault, probably I put to much fuel in it when I was trying to start engine with disconnected injectors :-)

We'll see tomorrow.

[Graham]

You should probably align the passenger side cam marks first (RH side when sitting in car), then check how far off the LH (driver side?) cam marks and balancer pointer are. If they are not too far out, then with cam marks aligned on RH side, set the distributor so rotor points at TDC mark (even if you have to remove and re-insert distributor to do that).

If the crank pointer is more than say 8deg off TDC, then you usually need to look at chain and sprockets for stretch/wear. Post pic of balancer pointer when passenger cams are aligned.

Is this a LHD or RHD car?

[szamik]

I aligned marks on RH side (cyl 1-4) and in that position, crank pointer say 15/16deg ATDC. Tomorrow I will check how it looks at other side 'cause now I have to go to work.

Car is of course LHD.

[Frank Reiner]

With all respect to Graham, the position of the cams vs. crank as shown is OK for engine operation; it will run.
The important relationship for ignition timing is breaker point opening vs. crank position, and hence, piston position. If the breaker point is opening with the crank as shown, and the rotor is at #1, the engine will run as far as ignition is concerned.

As Gertrude Stein (slightly paraphrased) reminded us a few years ago:
"A right hand is a right hand, is a right hand, is a right hand, is a right hand."
The location of the steering column is irrelevant.

[szamik]

Originally Posted by Frank Reiner

If the breaker point is opening with the crank as shown, and the rotor is at #1, the engine will run as far as ignition is concerned.

When breaker point should open? 5/10/15 BTDC?

[Frank Reiner]

Originally Posted by szamik

When breaker point should open? 5/10/15 BTDC?

The engine will run at any of those advance settings. Begin with 10 before, with both vacuum lines disconnected.

[Graham]

Originally Posted by Frank Reiner

With all respect to Graham, the position of the cams vs. crank as shown is OK for engine operation; it will run.

But Frank - The car doesn't run

It may not be the reason, but the timing is way off. His balancer pointer should be within about 5deg or less of TDC when the cam marks are aligned. You can get by with more, but at 15-16deg ATDC something is badly wrong. (I "think" One cam tooth = 18deg?). Woodruff keys are available for up to 10deg adjustment, but at that point, chain/sprockets/tensioner are usually changed.

Frank, did you see where the passenger (RH) side cam marks were when rotor was pointing to distributor mark? Unless I am reading the picture wrong, they were nowhere near aligned. Do you think that is OK?

szamik, you can continue trying to get car to run, but you have already done many things without any luck. It may not be your problem, but I would get timing as close to spec as you can. It isn't at present.

[Graham]

Originally Posted by szamik

I aligned marks on RH side (cyl 1-4) and in that position, crank pointer say 15/16deg ATDC. Tomorrow I will check how it looks at other side 'cause now I have to go to work.

Car is of course LHD.

At that point, where did the rotor point?

[Frank Reiner]

Originally Posted by Graham

But Frank - The car doesn't run

It may not be the reason, but the timing is way off.

Valve timing needs to be distinguished from ignition timing.
The valve timing is acceptable for engine operation; there is considerable wear of chain & sprockets, and the valve timing is late, but the engine will run.

His balancer pointer should be within about 5deg or less of TDC when the cam marks are aligned. You can get by with more, but at 15-16deg ATDC something is badly wrong. (I "think" One cam tooth = 18deg?). Woodruff keys are available for up to 10deg adjustment, but at that point, chain/sprockets/tensioner are usually changed.

Cam sprockets have 36 teeth. One tooth = 10 camshaft deg = 20 crankshaft deg.
Crank sprocket has 18 teeth. One tooth = 20 crankshaft deg = 10 camshaft deg.

Frank, did you see where the passenger (RH) side cam marks were when rotor was pointing to distributor mark? Unless I am reading the picture wrong, they were nowhere near aligned. Do you think that is OK?

The position of the camshaft marks is not relevant in determining ignition timing; the relationship of the crankshaft and the ignition rotor is relevant.

szamik, you can continue trying to get car to run, but you have already done many things without any luck. It may not be your problem, but I would get timing as close to spec as you can. It isn't at present.[/QUOTE]

[Graham]

Originally Posted by Frank Reiner

Valve timing needs to be distinguished from ignition timing.
The valve timing is acceptable for engine operation; there is considerable wear of chain & sprockets, and the valve timing is late, but the engine will run.

Cam sprockets have 36 teeth. One tooth = 10 camshaft deg = 20 crankshaft deg.
Crank sprocket has 18 teeth. One tooth = 20 crankshaft deg = 10 camshaft deg.

The position of the camshaft marks is not relevant in determining ignition timing; the relationship of the crankshaft and the ignition rotor is relevant.

Frank - You know more about these things than I do. I have a question - If valve timing is out by 15-16deg (a huge amount!), will there be compression when the pistons are at TDC? In other words, would both valves be closed? Manual says intake opens 5deg ATDC and exhaust closes 5deg BTDC.

I found where I got the 18deg from - Shop manual says "an offset of 1 tooth on camshaft sprocket results in approx 18deg at crankshaft". Could the chain be 1 tooth off on camshaft sprocket?

[rowdie]

szamik. Could you post a picture of the right cam alignment marks when at TDC? The current picture is not helpful.

[Graham]

Originally Posted by rowdie

szamik. Could you post a picture of the right cam alignment marks when at TDC? The current picture is not helpful.

Rowdie, In looking again at the pictures, perhaps both pictures are of the right hand cam. One with cam marks and one cam in general? I was confused too. Maybe szamik will confirm.

Camshaft on 1 cyl

And at the end....
Timing marks on passanger side.

If that last pic is the right side , then isn't surprising crank was out by 15-16deg when the marks were lined up?

[Frank Reiner]

Originally Posted by Graham

Frank - You know more about these things than I do. I have a question - If valve timing is out by 15-16deg (a huge amount!), will there be compression when the pistons are at TDC? In other words, would both valves be closed? Manual says intake opens 5deg ATDC and exhaust closes 5deg BTDC.

I found where I got the 18deg from - Shop manual says "an offset of 1 tooth on camshaft sprocket results in approx 18deg at crankshaft". Could the chain be 1 tooth off on camshaft sprocket?

There will be compression; the intake valve is the last valve to close on the compression stroke. It closes between 25 & 60 degrees (depending on cam profile) ABDC, consequently providing between 120 & 155 degrees of compression. The closing point of the exhaust valve is overlapped with the opening of the intake as the piston enters the intake stroke.

[Graham]

Originally Posted by Frank Reiner

There will be compression; the intake valve is the last valve to close on the compression stroke. It closes between 25 & 60 degrees (depending on cam profile) ABDC, consequently providing between 120 & 155 degrees of compression. The closing point of the exhaust valve is overlapped with the opening of the intake as the piston enters the intake stroke.

This is the page out of the manual. The 1973 Euro and USA versions had 117.982 engine except euro had higher compression. Should be the first 117.982 listed, I would think, without hydraulic lifters.

https://www.startekinfo.com/StarTek/outside/11883/PROGRAM/Engine/107/M117_45/05-215.pdf