Autozen, you really seem to know my car. Thanks for every thing.
No real work done yet, 50MPH wind and 21*f outside. But I still looked at the car.
Fiddled with some vac lines, since no one has a vac diagram for a 73 450sl FED. Haynes is mostly generic.
Dist. vac line goes to a switch over valve, mounted on pass. side near coolant pressure tank. then from there it goes to the base of air intake (where the air filter mounts). Replaced that line.
Took the dist. cap off for ignit. point inspection. Points all brand new even has a little semi clear plastic protector over the contact area.
Inspected the inside of the cap. WaLa I found all kinds of water droplets on the inside of the cap. This has to explain the very rough running. I will contine with the dist. work this weekend.
One question- there are 2 more switch over air valves(shaped like large acorns) mounted close togather on the mid to pass. side fire wall.
One has a vac line on top with 2 vac lines & electric connector on bottom.
One of the bottom vac line ports is open (nothing connected to it) the other one has
a red vac line to it but goes 10" and is pluged with a wood screw. Seems weird.
The 2nd. switch over valve-has a line on top 2"long and goose necks and is left open, the bottom has 2 vac lines connected, one goes to the lower part rear intake manifold. The other tees off in many directions, one tee goes to a small plastic check valve, then continues. Does any of this seem right?
Thanks

__________________
Stable:
1973 450sl
1978 red diamond ice vette
1975 steel blue convertable vette
2002 steel blue dakota quad.

go here:

http://www.peterschmid.com/

vacuum schematics for Mercedes are within

Thanks Oxymoron: Great site but they have nothing old enough. The 73 is before all the smog stuff was needed. Thanks

__________________
Stable:
1973 450sl
1978 red diamond ice vette
1975 steel blue convertable vette
2002 steel blue dakota quad.

Right.

One of the pictured vac valves is not, however hooked to the smog stuff and I thought one of yours might be analogous to it.

I believe one of them may advance timing slightly when the AC compressor engages and thus increase idle speed?

Also, though hard to read, the vac hose color codes are contained in the diagram and thought you might be able to deduce which ones were applicable to your engine.

http://www.peachparts.com/shopforum/showthread.php?t=86330&highlight=vacuum+diagram


look at post #2

wrong motor and its a carburetor car, but correct vintage and sounds like your setup

JBR:

Your car has the simplest vacuum set up of all. Unfortunately the vacuum schematics are broken up and scattered all over the service manual with various systems. The two units on the firewall are for the heater controls. The levers on the console operate micro switches which activate the vacuum solenoids to either open the heater valve or close it. The default position for the valve is open for heat.

The solenoid on the passenger side is dirt simple to set up. The line to the manifold supplies vacuum to the solenoid. The other line to the distributor gets the vacuum to the distributor when needed. The electronics detemine when this all happens. At temps above 100C there is no vacuum to the distributor. At temps below 100C there is vacuum to the distributor. When the AC is on there is no vacuum to the distributor. And, at all speeds above idle there is no vacuum to the distibutor. When there is vacuum to the distributor it retards about 12 degrees. When the vacuum is off it advances for cooler running and better fuel economy.

From the above you can see the system components that affect distributor vacuum: the temperature switch, the throttle position switch, and the AC switch. When these are working properly the system is operating as MB intended.

That said, the simplest way to improve your car's performance is to try to set the timing to mimic european versions. And, the simplest way to do this is to time it, without the vacuum line connected, to about 32-34 degrees BTDC at 3,000 rpm. After making this setting you can re-connect the vacuum line and let the retard systems do their jobs. They only operate at certain times and even then they are not adverse to your performance. The US versions limit distributor advance to about 18-20 degrees total; when the vacuum is off to the distributor this is all you can get from your US version distributor. European models have more advance built in so with the initial lead there is about 32-34 degrees at 3,000 rpm, hence my suggestion to use this as your baseline. Fine tune it a bit for your gasoline.

For what its worth...

230/8

p.s: you need to invest in the MB CD ROM service manual. It is only $20 from MBNA. It is available here by mailorder: http://www.classictechlit.mbusa.com/MB/

Thanks that is a great tread, wrong engine but looks like some stuff is simalar.

__________________
Stable:
1973 450sl
1978 red diamond ice vette
1975 steel blue convertable vette
2002 steel blue dakota quad.