Just to get the ignition system running optimally I got the advice to ditch the 40 year old stock black Bosch coil and go with a higher output Pertronix Flamethrower coil to match the Pertronix Ignitor electronic ignition module already installed. Shouldn’t be too hard. I got the 3 Ohm version that will match the desired input of the Ignotor module. To run that I need to make sure I’m sending it a max 14 volts but over 12. The Bosch coil wanted less so BMW put a resistor wire in the car to reduce the voltage. Where it gets interesting is the ran 2 wires to the coil. One gave it 14 volts at startup for easy starts then once the car started it switched over to to other lead with a reduced voltage. All that business I want to get rid of and just run it at the higher voltage since the new coil wants more voltage. To do this I located the resistor wire which is a 1 meter run of copper wire and remove it and replace it with standard wire.
While led I am in there I am going to clean up the wiring and move the coil from the front of the engine bay to the rear near the firewall where it is optimal. I bought a new coil bracket from OReilly’s for about $5. I got the coil online through Amazon for $35.
I started out out drilling holes for the new location. Pretty straightforward, just mark and measure twice and drill once. Once the coil was in place I then carefully removed the negative wires and measured them, cut them down, added spade connectors and heat wrap.
I then traced the resistor wire back to its connection point and replaced it with a standard copper wire. Then I repeated the other steps. Measured, cut, spade connectors and heat wrap. I then replaced my longer coil to distributor cord with the shorter one that came with my wires from Ireland Engineering. (thanks Ireland!!) The last step is to remove the old coil and bracket, connect the battery and fire it up. Before i did that I double bad triple checked I had the positive and negative wires connected properly. This done improperly will fry the ignition module…not fun!
So all things looked good, turned the key and it fired right up! Nice!!! The difference? Subtle, yet noticeable. Smoother idle, smoother power delivery and it feels like I have more low end grunt. At first I thought this thing isn’t making a difference because it’s smoother but once I realized I sprinted to 90 mph and it was humming right along I realized I was just getting through the RPM more effortlessly. In addition to the slight performance improvement I also get the added benefit of a cleaner engine bay with less wires and a tidier appearance. A win/win in my book. Now maybe I need to start preparing to repaint the engine bay!!! Nice mod…on to the next!!!