Next step:
Crank trigger and 36-1 toothed wheel.
I'd been having some random issues with the Hot-Spark electronic ignition interference and the Megasquirt's ECU. Sometimes the tachometer reading to the controller would just go crazy and show 16K+. Needless to say this caused havoc with the fueling.
Tried everything I could think of and all the "fixes" from the web. Resistors, diodes, condensers, filters, power settings, distributor caps, rotors, re-work the grounds/power feeds, Pertronix ignition unit, voltage regulator, plug wires and routing, you name it. Never solved the problem.
Decided to finally go to a trigger wheel Hall-effect pickup. Wish I'd done it to start with.
The deep fan belt pulleys used by Mercedes make it a bit awkward to simply use spacers and mount the trigger wheel on the front of the crank shaft. I didn't care for making a long bracket and mounting the sensor in the air stream of the cooling fan. Long wires, air flow, water being thrown by the fan all seem to lead to problems.
Time for some creative thinking. The pulleys are a bell shape and there is adequate room between the first pulley edge and the front of the crank dampener. The pulleys are held flush to the dampener by three bolts. There are six threaded holes in the dampener so you have some leeway in the mounting. This comes into play later.
I designed my own wheel and had it made at a local shop but they are available from :
36-1 Trigger Wheel - Miller's Mule
I made a 5" wheel but a 6" wheel would work.
Dimension for the center bore is 90MM.
The wheel is made from 3MM plate stock (1/8" mild steel). It must be ferrous so don't even think about aluminum or stainless steel. Yes, some stainless has ferrous qualities but why tempt fate?
Photos and further steps are upcoming.