Anyone who has removed the ignition coils from their stock 1.6 Miata can tell a story about how difficult it is to remove the bolt holding in the coils from behind the engine. I know 1.8 litre cars have the ignition coils on the other side of the engine and I wonder whether they have the same problem. On the 1.6 there are three bolts in total, two up on the valve cover and a very inaccessible third bolt wedged tightly in between the firewall, thottle cable and the engine.

That is the reason why most people do not reinstall that bolt with the coil package. On the Miata forums some owners claim never having encountered any problems with this practice. Others report cracked valve covers that probably stem from the coil pack being free to vibrate along the lateral axis when only held in by the two bolts on top.

I don’t think getting a used valve cover for a Miata would be too hard, but I like to do things the right way. I had managed to loosen this bolt with a common combination wrench, but threading the bolt back in with the coil pack installed proved impossible to me.

So I decided to heed the advice on the forums and modify the coil pack in a way that would allow me to thread in the bolt with the coil pack removed, then slide the coil pack over the bolt and tighten it down. To do this, you need to cut or file a hole in the mounting point on the coil pack. I used a dremel to do this.

After that was done, I threaded the bolt and a washer back in. The thickness of the mounting point is 13 mm, so I left that much thread plus a little bit. This way the coilpack slides right over the bolt and after putting in the two top bolts all that’s left to do is tighten our third bolt.

This 12 mm nut is just the right length. There is a surprising amount of room to turn the wrench.

I found a good way to do this is with a small quarter inch socket wrench put inside the small gap between the heater core hose and the speedometer cable. I tried not to bend either of these too much in order to not mess up my speedometer or my heater core.

After a bit of cussing and hopefully not scratching your hands too badly everything should be bolted down and free of movement and vibration.