Aldon "Amethyst" Mappable Ignition System
Frequently asked questions

Is Amethyst suitable for positive earth cars, or 6v electrics?

No, 12v negative earth only.

Does Amethyst require a crank trigger?

No, Amethyst is designed to trigger from the distributor.  This greatly simplifies installation and setup.

Can I use Amethyst with my existing electronic ignition system?

In most cases, yes.  We have Amethyst units working successfully with Aldon Ignitor and other Hall effect triggers, optical triggers including Lumenition and Piranha, and reluctors.  You can find information about the Amethyst input circuit in Appendix D in the instructions.  Please contact us if you would like any further information about compatibility with your car.

Do I need to retain the amplifier from my existing electronic ignition system?

No, if you have a Lumenition or other system with a separate amplifier, you can normally trigger the Amethyst from the original sensor and then connect the Amethyst directly to the coil.

Is there any minimum or maximum number of cylinders?

Amethyst units are in use with engines with 4, 6 and 8 cylinders.  There should be no problem in theory with twins or triples (or fives!), but we have yet to install one.

Will Amethyst work with an uneven-firing 90 degree V6?

Not easily.  The unit is designed to work with engines that have equal firing intervals between the cylinders.  However, if the engine has two coils and a double set of points then it might be possible.  Please call us to discuss.

Can I specify an advance curve to be pre-loaded into my Amethyst?

No.  We recommend that you begin with the official advance curve for your vehicle.  A selection of maps may be found here.  However, each Amethyst unit contains a default map which will get you running.

Can I pre-load an advance curve into the Amethyst unit before fitting it to the car?

Yes.  Just supply +12v to the Amethyst red wire, then the unit can be connected to your computer via USB.

Will my existing HT leads and coil be suitable?

For best results, we recommend that quality silicone type leads should be used with a 1.5 to 3.0 ohm coil.  Also, replace the rotor arm and distributor cap if they are not in good condition.

Should I set static advance to TDC, or the manufacturer's setting?

They both work equally well.  If you use the manufacturer's setting, then the map can be entered simply by copying the figures from the workshop manual.  If you use TDC, you will also have to type the static advance figure into the "offset" box.

Can I change the default figures for RPM limit and maximum advance?

Yes, you can type your own figures in place of the default limits of 5,000RPM and 34 degrees total advance.