Update for Autozen & Tomguy

[JBR]

I did step by step as you layed out Autozen. Well It really wants to start but no start. So I truned the dist. full counter clockwise, It is hard for the car to turn over, like a weak battery. So I turned the dist full clockwise, engine spins more freely and now almost starts. Now before I pull the dist. and turn the rotor which way should I turn it (the rotor that is).
By the way with the cam washer mark and the tower mark lined up it read about 3-4* to the left of the pointer (ATDC). The chain is new before I got the car and really seems tight, the guides look new. I'am getting closer
Thanks

[JBR]

I have not done anything yet since the last post but think and read. When I bought the car and drove it home in Nov 05 it ran fine but rough. And since I have started to mess with it I have noticed, That the air temp switch (2 wires) in the air cleaner horn were never hooks up, also the 100*c water temp switch (per Performance products) its the auxillary fan switch.was never hooked up. I have them hooked up now.
It seems as if something is keeping the timing too advanced.
I read in the Haynes manual. To check the water temp sensor.
(per Performance products) its the axullary fan switch. Per Haynes ist the 100*c temp switch. Take the one wire off and ground it, it should increass the rpm and increass timing 12* (advance).Since I can't start the car I can't check the timing. But with the work done above it should be at TDC.
I checked the wire going to the 100*c temp switch. It is a ground wire, I have continuity between the wire and ground, with key off. Checking the one post on the switch I do not have continuity to ground.

[Tomguy]

None of this is importnt to you yet. The entire ignition advancing/retarding I dont think is in effect while cranking - not enough vacuum at the throttle body to produce the required vac. If you hook a timing light up to it now, TDC should be more than enough to get it started. The air temp sensor is for the mixture, but won't really affect your startup (or prevent it from starting). The aux fan switch (the sensor with just 1 wire) only kicks on (continuity with ground) at higher water temps. This shuts the vac to the distributor off (advancing the timing) and turns on the aux fan. If you want to test this, with the key on the run position, short this wire to ground. Your aux fan should kick on.

It sounds like turning the dizzy full counterclockwise advances it too much to start, and full clockwise retards it too much. Try somewhere in the middle. Hook a timing light up and check for TDC if need be (dont set it at 5deg or it might stall once it starts when the vac is applied to it, retarding the ignition slows the engine).

[JBR]

Tomguy: It sounds like you think that my manifold vacuum might be in question.
Here is what I'm going to do.
Install new plugs even if not needed.
Replace main vac line from rear engine to MAP sensor.
Get it started some how. check vac pressure on manifold. This car seems to have only have 3 vac ports. One large going to Map. One small rear of manifold going to heater control switch over valves and one small on throttle body going to dist. switch over valve. I should most likely pull my vac test from the rear of manifold. I'll keep pluging away. thanks

[Tomguy]

No, your manifold vac is not in question (yet, anyway).

The line off the throttle body that goes to the switch on the firewall is for your distributor's vac advance. I just don't think it produces enough vac from this while cranking to fully retard your distributor.

Your MAP sensor vac shouldn't affect startup either. even without a vac at all going to your MAP, your engine will still start.

I dont know where vac goes to on a 450SL but I know where it goes from on my 108 4.5:
From the manifold to the: Tranny, Door locks, MAP sensor, brake booster.
From the throttle body to the switch on the firewall, then to the distributor.
The switch on the firewall turns vac off at certian conditions (such as when your 212F switch goes on).