Ignition: What is THIS???

[blairwag]

Hey gurus,
1971 280SL ignition system, was Transistorized. It fried in 1974 and was retrofitted with a make-shift traditional Kettering MB ignition at that time. Now, I'm trying to convert to Electronic Ignition, using Crane's XR700. I have the XR700-0231 install kit and instructions. I can recite them from memory. I have John Hassel's install supliment as well.

Can you help me identify the following. This picture shows 4 thing-a-ma-bobs to the right of the ignition coil. They look important. What are A, B, C, and D. I realize that E is the ballast resistor. Oddly, the ballast resistor is a 0.9 ohm, rather than the 0.6 ohm that's called for by the BBB.

Download Attachment: Things.jpg
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...what are these things? What do they do? How do they work? How are they wired? How can I make sure they are working with the system?

Also, there is this 2 terminal connector block, which is attached to the original Transistorized module'd mounting plage, under the batter shelf. This thing has a lot more wires connected to it, than John's doc suggests. However, the wires don't seem to do much. One terminal seems to be connected to ground. The other is a total mystery. The terminal closes to the rear of the car is connected to ground, with a bunch of wires connected. None of which seems to lead to the points. The terminal closest to the front of the car has 2 wires. It used to have 4 wires. One was cut - no idea where it went. One when to the transistorized module. I removed that with the module. The other is black with a green wire inside. It goes no where. Was this SUPPOSED to go to the speed relay? Where is the speed relay? The other wire (the last one) runs into the larger wiring harness up over the driver side wheel well. What does that go to?

Download Attachment: TerminalBlock.jpg
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Also, is that heavy cable that runs to the engine block, just behind the power steering pump - is that the speedometer cable?

Finally, where does the Tachometer wire run to? I can't find it. Mine is currently hooked up and working (it was before I started, at least). Id like to know where it is connected, and to what, so I can be sure not to disturb it.

Download Attachment: WideView.jpg
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Thanx, in advance (TIA) for any and all help. You guys are awesome.


--
~~~~~~~~~~~~~~~~~~~~~~~~~~~
William Blair Wagner: blairwag@earthlink.net
Education is not always knowing the answer,
...but rather knowing where to look for it!
1971 280SL US Automatic
~~~~~~~~~~~~~~~~~~~~~~~~~~~

[isofast]

Red coil calls for 1.8 ohm ballast resistor. Your picture depicts a Bosch red coil.

First Place AACA Show Winner 350SL July 2003
I love low mile Mercedes.
1969 280 4spd Papyrus White

[hands_aus]

Hey William,
I have a .PDF file that discusses the Crane system and the 1969 280 sl ignition system. It shows how the connections were made to the MB Electronic box. It also discusses the way the kettering system works both with 2 resistors and single resistor.

I can email it to you, but it is 750KB in size so be aware. Let me know if you want it.

Bob (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[blairwag]

Hi Bob,
I have the documednt you mention, its the Crane XR700 installation tips by John Hassel. It's an invaluable document.

What I need to do is identify the other things, like speed relay, engine rpm and vaccuum actuated switches, etc. that work with the engine and the ignition system to make the car run correctly.

Can you, or anyone, identify any of the components in the things.jpg?


--
~~~~~~~~~~~~~~~~~~~~~~~~~~~
William Blair Wagner: blairwag@earthlink.net
Education is not always knowing the answer,
...but rather knowing where to look for it!
1971 280SL US Automatic
~~~~~~~~~~~~~~~~~~~~~~~~~~~

[hands_aus]

hi William,

A is the speed relay
B i am not sure .......there is a time relay somewhere
C two way valve
D relay for Cold Start Valve on Inlet Manifold

Might be a good idea to mention your distributor model too.

My 250 sl has a 051 dist with a 0.9 ohm resistor that is in circuit all the time.
The battery comes from the switch to the input side of the resistor and the output side of the resistor goes to the coil input. My car has no emission control relays like the speed relay.

Is that how your current system is wired?

It seems to me that your speed relay is not working. I say that because it needs to pick up a contact on the missing MB box.
The Crane system needs to connect to that same contact for the speed relay to work.

The Tacho cable goes to the engine block behind the injection pump.
The speedo cable goes down to the back of the transmission.

Do you want a copy of the wiring diagram for the 280sl?

Bob (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[blairwag]

Hi Bob & any other interested readers,
Yea, I should have mentioned the Dist#. I post so much crap, that I try not to make it all read too long -else no one will read my crap and thus I'll get no help. You know?

Also, yes, I know the ignition coil is the Bosch Red. It's part of the conversion. I just put that in last night.

1971 280SL with "0 231 185 010" aluminum body replacement distributor.
Keep in mind, this is a 280SL with a chopped up ignition system. It was chopped by a pro 20 years ago when the transistorized module got baked. So, now, I need to un-chop it, while at the same time, I retrofit the Crane XR700.

I was afraid the speed relay might not be working due to improper connection. But I don't know how to test it because I don't know how it works, what it does, nor how it's PROPERLY connected.

If you have the 280SL wiring diagram, and it shows more than just the key-switch, transistor-module, coil, ballast resistor, and distributor, then YES - I'D DESPERATELY LOVE TO HAVE IT. If it's as basic as just the ignition parts mentioned, then I already have something.

I have the BBB, but it doesn't show a schematic nor wiring diagram that includes the speed relay, two way valve, cold start valve relay, and mystery box (B). Atleast I can't find it. If it's in the BBB can you refer me to it. If it's not, but you have such a thing, can you send it to me in some form? (mailto:blairwag@earthlink.net)

I've spent a lot of years around old US cars. I thoroughly understand basic ignition systems.
Unfortunately, I really have no experience with mechanical FI, cold start valves and relays, speed relays, and two way valves.

What does the speed relay (A) do, and how is it SUPPOSED to be wired (electric & vaccuum)?
What does the mystery box (B) do, and how is it SUPPOSED to be wired (electric & vaccuum)?
What does the two way valve (C) do, and how is it SUPPOSED to be wired (electric & vaccuum)?
What does the cold start valve relay (D) do, and how is it SUPPOSED to be wired (electric & vaccuum)?


--
~~~~~~~~~~~~~~~~~~~~~~~~~~~
William Blair Wagner: blairwag@earthlink.net
Education is not always knowing the answer,
...but rather knowing where to look for it!
1971 280SL US Automatic
~~~~~~~~~~~~~~~~~~~~~~~~~~~

[jeffc280sl]

Hello Bill,

I have a 1970 280SL with the 010 distributor.  I recently replaced the transistorized ignition with the Crane unit.  I also recently replaced my speed relay with an after market unit because it was not working.

I'm pretty experienced now with the ignition and emission system and I have a fair amount of documentation that I will be happy to share.

Here are some answers to your questions:

The speed relay interacts with the two way valve and 8 pin relay which sits across from it. The two way valve provides vacumm (retard)to the distibutor and it is wired to pin 1 and 3 of the speed relay.  Pin 3 is ground and pin 1 is +12V when switched on.  Pin 4 of the speed relay is wired to the #1 coil lug.  At 2400 RPMs the speed relay, which recieves RPM inputs via pin 4, provides +12V to pin 1 which turns on the two way valve.  In the on position the two way valve removes vacumm and provides atmospheric pressure to the distributor which removes the retard.  This circuit is part of the emission system.  There is a real simple test for the speed relay.  Get a 12 V lamp and solder a 6 foot or so wire to the plus and negative sides of the lamp.  Remove the connector to the two way valve and insert the other end of the wire into the connector,  Re-insert the connector on to the two way valve and close you hood with the lamp on the outside of the engine compartment.  Go for a drive.  At 2400 rpms the lamp should turn on.  Someone told me it is neccessary to drive the car because the automatic trans provides some sort of fluid pressure input to this circuit.  Mine is a 4-speed and I don't need to drive it.  I simply rev the engine.  Go to 00-74/4 in the BBB for an explanation.


The 8 pin relay is also part of the emissions system.  I can provide you with a wiring diagram.  A written explanation would take too long without it.

The cold start valve simply provides a mist of fuel in the intake manifold during engine cranking when the engine is cold.  The silver box is a simple relay which is wired to the cold start valve solenoid.

I'll gather some docs and email them to you.

Jeff

Jeff C.
1970 280SL 4-speed

[blairwag]

Hi Jeff,
That information is immensely useful. Thanx!  Yes, PLEASE, email me whatever doc you have: mailto:blairwag@earthlink.net.  Thanx, so very much!


--
~~~~~~~~~~~~~~~~~~~~~~~~~~~
William Blair Wagner: blairwag@earthlink.net
Education is not always knowing the answer,
...but rather knowing where to look for it!
1971 280SL US Automatic
~~~~~~~~~~~~~~~~~~~~~~~~~~~

[blairwag]

All right! With the kind help from Jeffrey Clute, Bob Smith, and Bob Brisbane, I am armed and dangerous!

One question before I begin:  What prevents me from eliminating the Two-way valve and it's relay support all together, and just plugging up the line to the distributor vaccume retard diaphram?  This will simply eliminate the vaccume retard at low speeds. Big whoop! I don't drive the car enough to be concerned about low RPM emissions - besides, I burn so much oil - that's more of an emissions concern.  Your thoughts.

Anyway - here's the long explanation, as I now understand it all...

Identification:
A = Speed switch (4 see fig 00-76/7)
B = Relay switch (5 see fig 00-76/7)
C = Two-way valve (9 see fig 00-76/7)
D = Working current relay (29 see fig 00-76/7)

Details Source: BBB 00-76 (for my 1970/1971 280SL w/Automatic). The automatic seems to have a lot more *CRAP* than the manual transmission equipped SL. Ugh!

Function:
When the temp sender on the thermostat reflects temp below 100 degrees C and the temp sender on the rear driver side of the block reflects temp above 17 degrees C, the Relay switch (5) receives 12V on pins 5 & 6, relative to pin 8 (I guess 8 is reference, or ground). If engine coolant temp is below 17 C or above 100 C, then 0V is applied to pins 5 and/or 6 respetively. This collapses any signal/power to the two-way valve (9), causing no vaccume (retard) to be supplied to the distributor. Ignition is now advance. This is NOT the normal mode of operation.

When engine coolant temp is between 17 C and 100 C, 12V is applied to pins 5 & 6 of the Relay switch (5). When Speed relay detects RPM signal 2400RPM or higher on pin 4, from the 1 connector on the ignition coil, it applies 12V to pin 1 of the two-way valve, from it's pin 1, as supplied to it's pin 3 from pins 3 & 7 of the Relay switch (5). The 12V to pin 1 of the Two-way valve energizes the valve, allowing it to cut off vaccume to the distributor vaccume retard diaphram. This allows the switch plate to run in the distributor to it's natural position, and allows for advance ignition. (see 00-74/4 A. Description of System for simpler explanation, 280SE auto is same operation as 280SL auto)

The Working current relay (29) seems to work with the Speed switch (4) and Relay switch (5) to control Fuel shutoff (stopping solenoid) of the injection pump during decelleration until engine RPM drops to 1250RPM.

There are other controls involved in the emissions control system, including the Idle Throttle switch on the induction venturi, the Start lockout switch on the firewall, which work with the other switches as well as the oil pressure sending units on the engine and transmission.

Now, my problem is going to be in finding the wires that connect all this. I've already located a green and black wire-in-wire that is not connected, comming from that 2 terminal block on the transistorized module mounting plate; AND a large red wire that leads from a large wire harness intersection, on the driver size wheel well. This red wire  plugs into this intersection via a male tongue that pushes into a female wireless connector. No clue what it was for. But, after nailing all this down, I'll be able to get it working right again.


--
~~~~~~~~~~~~~~~~~~~~~~~~~~~
William Blair Wagner: blairwag@earthlink.net
Education is not always knowing the answer,
...but rather knowing where to look for it!
1971 280SL US Automatic
~~~~~~~~~~~~~~~~~~~~~~~~~~~