The Kettering ignition systems (points & condenser) that was used on vehicles into the 1970s is a weak point in the reliability of many vehicles. For these vehicles, upgrading to an an electronic ignition system is an easy and straightforward modification. The advantage to electronic ignition is improved reliability, reduced maintenance, improved fuel economy, and reduced emissions.
Later Ignition System Swap
A simple way to upgrade to electronic ignition is to find a later version of your engine that already has electronic ignition and swap over the entire wiring harness for the ignition system. You may also want to upgrade your charging system to electronic voltage regulation as well if you have a parts car at your disposal. To maintain your vehicle's performance and emission characteristics, you should ensure that the mechanical and vacuum advance in the electronic distributor is identical to the one in your mechanical distributor. Potentially, you may be be able to improve your vehicle's fuel economy and power with a different ignition advance curve but at the cost of possibly poorer emissions. I recommend that you try to keep your new ignition advance curve as close to original as possible.
As an alternative to swapping to a later model ignition system, you may also consider upgrading with a Pertronix ignition system. This upgrade is extremely simple and even easier than swapping to later model ignition system. This ignition upgrade consists of a parts package that replaces the points & condenser with a electronic components and therefore maintains your engine's existing advance curve. An electronic pickup replaces the breaker points and a magnetic sleeve slips over the distributor shaft and covers the point cam. Your should also consider replacing your existing coil with a Pertronix coil (which has higher internal resistance) so that you can eliminate the primary resistor. Please contact Pertronix for application advice.
Even if you have an electronic ignition in your Chrysler vehicle, you may want to upgrade this to an HEI ignition controller. This will allow you to have an even hotter spark without the need for the ballast resistor. See HEI Electronic Ignition Retrofit How-To for more information.
Programmable Ignition Systems
For those vehicles for which parts are hard to find, another ignition system option is an aftermarket digital ignition system. The MegaSquirt-II™ EFI Controller supports a variety of different ignition systems. You can use the ignition controller capability of this EFI controller without having its EFI capability. For more information, see MegaSquirt Ignition Control.
In conjunction with the MegaSquirt project, the fully programmable stand-alone MegaJolt Light ignition system is another option, . A commercial version of this ignition system is available from AutoSport Labs. This system requires the use of a 36-tooth wheel mounted on the crankshaft, with one tooth missing in order to provide crankshaft synchronization.