Electromotive Ignition Sensor Mounting

I came across a deal on an Electromotive ignition module, so I figured it would be a fun, challenging modification to make to my engine. Instead of a distributor and coil, this works off of a "trigger wheel" - a metal disk - that's mounted on the crankshaft. A magnetic hall effect sensor can determine both engine RPM and TDC - the control unit has coil packs and fires the spark plugs directly.

Anyhow, I now have to figure out how to mount the trigger wheel and the magnetic sensor. There is a metal spacer between the fan hub and the fan, so I figured an excellent solution would be to replace this spacer with the trigger wheel.

My new oil galley plugs on the front of the oil filter mount seemed like the perfect place to fashion some kind of sensor mount. I got some plugs that have a recess for an Allen wrench - this enabled me to weld a stud onto them, and then weld on a large nut to provide a) a way to tighten down the plug, and b) a surface to bolt the bracket to:

Faricating a mount for an Electromotive ignition on a Porsche 914 engine

 

Next, I started fashioning a bracket out of aluminum (it's easy to machine and doesn't interfere with the magnetic sensor):

Faricating a mount for an Electromotive ignition on a Porsche 914 engine

 

My mounting holes are oblong slots for adjustment. And here is the block that will hold the sensor (which will slide up and down for adjustments):

Faricating a mount for an Electromotive ignition on a Porsche 914 engine

 

A quick check to make sure the bracket clears the fan shroud, and you can see the trigger wheel on the hub:

Faricating a mount for an Electromotive ignition on a Porsche 914 engine

 

The trigger wheel is 0.040" thicker than the original metal spacer, so I machined down the mating surface of the fan to accommodate for the thickness difference:

Machining Porsche 914 fan on a Bridgeport vertical mill

 

The fan clears the bracket, too!

Faricating a mount for an Electromotive ignition on a Porsche 914 engine

 

Here's the clearance on the back side of the fan shroud. Mission accomplished.

Faricating a mount for an Electromotive ignition on a Porsche 914 engine

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All pictures and text copyright 2008